Ask Lucas

Lucas CannabiNerdPosts: 294
edited January 2013 in Hydroponics
Hello friends

In the interest of destroying my undeserved reputation as a know it all, I offer myself as the majdub.

Ive grown old and tired, seldom posting to repeat myself anymore, but, I will try to answer any questions people may care to explore, with my considered, and considerable, opinions.

I would particularly prefer, if anyone else has the answer to basic Lucasisms, if others would post before me. It helps me a lot when I dont have to answer questions that could have been answered by a considered reading of my, again, considerable signature links.

in the spirit of passing on the torch of learning with good will

hit me

***note -> [URL=""]here is a link to the archived version of this thread ... makes it much easier to print out or save for future reference***

***also [URL=""]here is a thread showing how to print long threads like this***
Post edited by Lucas on


  • guest Posts: 24,389
    edited July 2014
    SV0Ld 9l61XK
    Post edited by Unknown User on
  • Indica SativaIndica Sativa Member Posts: 68
    edited May 2006
    Lucas, your the man! Don't let anyone tell you otherwise!

    Since ebb/flo seems to be your area of expertise, I was wondering what your current thoughts and opinions are in regards to changing out your reservoir? Should I bother changing it out? Or not...? Is the 5 ml, and 8 ml of Flora Nova Bloom still the standard when it comes to veg and flower?

    If anyone has any links for the addback formula or any info regarding it, I would be more then grateful =]
  • Lucas CannabiNerd Posts: 294
    edited May 2006
    Hello cb

    good to chat with you

    majdub is fool of god, as in Sufism, the Mullah Nasrudin is a Majdub. (the link has fables, I dont recommend reading the interpretations) Majoum is cannabis edibles, which Majdubs consume to bring them closer to god.

    The current Lucasized Formula with GH Flora is still 0-8-16 as you said. Other nutes, such as PBP can also be made to approximate similar NPKMg values, for example PBPBloom @ 15ml/gal plus 5ml/gal Cal Mag.., or 8ml/gal Flora Nova Bloom

    Both with target TDS @.7 of about 1300ppm (use less FNB, like 6ml/gal if your TDS exceeds 1400 with 8ml)

    The original reservoir strategy I learned from pH was to dump and replace as you described, once an equal volume of addback water has reached. IOW, when a 20 gallon res, got 20 gallons of top up water, the res was dumped and refilled at fresh 0-8-16. This was not with pH adjusted water, because it works best to allow the res pH to fluctuate within a range of 5.3 to 6.3

    An alternate reservoir management strategy I now prefer, is to add nutes to the reservoir in the addback water. The goal is to bring the reservoir back up to 1300ppm. In this strategy, I feel a single res change at harvest is sufficient.

    Despite the obvious concern that this non dumping approach allows toxins to build up, I never experienced toxin buildup. this surprised me and caused me to alter my thinking about plant metabolism. It seems they do not excrete toxins the way organisms with digestive tracts do.

    How much nutes goes in the addback water varies by res to light ratio. For example, a 50 gallon res under a single 1k can be topped with 33% of 0-8-16, and the 1300 tds will be approximately achieved... Im not a stickler for that number, and am happy fluctuating anywhere between 1100 and 1500ppm over the course of a week, such that if one chooses to top only with water for a few days, the nuteing can be done in a single session each week.

    If the same 50 gallon res is used under twice as much light, it will probably require twice as much nutes in the addback water.

    The most primary concern is to achieve the TDS increase, while staying within pH range

    adding nutes lowers pH, so sometimes one can avoid pH adjusting, by adding more or less nutes
    adding water raises pH, so dont adjust a reservoir, until it is topped up with water and nutes

    > What size trays would you suggest?

    I think in terms of 4x4 footprint per 1k, although with high plant numbers, it can work with 3x3 footprint

    so for a 2k project, either a 4x8 or 3x6 table

    plant numbers vary by veg time. with 3 weeks of veg (counting starts the day rooted clones are transplanted), 10-12 plants per 1k is enough. With 1 week of veg 30-40 plants per 1k is enough.

    disclaimer, plant numbers increase legal penalties. I do not encourage you to break the law, you should only use my advice if you are a qualified patient and are able to cultivate legally. However, even then, Federal Law still makes cultivation in the US illegal. Dont break the law on my advice.

    The suggested amount of medium per 1k is 30-50 gal, so 10 three gallon pots is the same total as 30 one gallon pots

    > What media would you recommend- corn, coir/perlite, rockwool, etc…?

    As a hydroponics medium, I prefer clay balls
    other denser mediums work if they are not overwatered

    > As a corollary: if rockwool is an option, what size cubes will produce the most productive results?

    Other than cloning in a dome, I have no positive experience with rockwool in larger blocks. It usually succcumbs to algae, which is a breeding zone for many problems. I do not recommend blooming in rockwool. But Im sure there are others with more experience than I have working with it, that can contribute their safe operations parameters.


    Hello IS

    thanks for your kind words, and for giving me a forum for my opinions

    > I was wondering what your current thoughts and opinions are in regards to changing out your reservoir? Should I bother changing it out? Or not...? Is the 5 ml, and 8 ml of Flora Nova Bloom still the standard when it comes to veg and flower?

    I dont think it is necessary to change out the reservoir until harvest. But it should be kept full, so the nutes dont get too concentrated. I dont have a weaker formula for veg.. The only time I use weaker nutes is under fluorescent lights.

    I did at one time create a complex mathematical formula to predict how much nutes you need to addback for a given res TDS. But rather than recreate it, I invite someone to post it.

    The main concept is to bring the TDS back to 1300-1400.

    Here is a practical example.

    Imagine a 1k light with a 50 gallon res, starting at 1300ppm. The nute is FloraNovaBloom in RO water @ 8ml per gallon, plus about 1-2ml of pH UP per gallon.. depending on the type of pH UP you use... I think Earth Juice Natural pH UP works fine, so does GH brand pH UP

    Each day for 6 days the res is topped up with plain RO water. After adding the water, a TDS reading is taken. If its more than 1100, dont bother adding nutes unless you like the task. (how fast the TDS drops depends on how big the plants are, just focus on the TDS number, not the number of days in this example)

    On day 7 a TDS reading shows 1000 ppm, so a guesstimate is made that 2ml/ the 50 gallons res size (thats a little less than 33%) , might bring the TDS back to 1300.

    So the gardener puts 100ml of Flora Nova Bloom into the res, waits a few minutes for stirring, and does a TDS reading.

    If it comes out to more than 1300, then the operator uses less than 100mls the next time TDS drops to 1000

    soon a pattern will emerge, and nutes dosing becomes predictable, both for pH and TDS

  • guest Posts: 24,389
    edited May 2006
    i never thought of you as a know it all....on the contrary, you seemed to have lots of knowledge and eager to help others succeed with less ego than anyone i can think of.

    one of the first things DSOTM told me when i started growing again was to read everything Lucas has written and it's served me VERY well.

    so no question, just a thanks for what you've done for the whole cannabis community.

  • Indica SativaIndica Sativa Member Posts: 68
    edited May 2006
    Mix #2 This might get a little confusing... added all supplements in this exact order! All of them are Botanicare also.. no Flora Nova in this mix.

    I started off with 1 gallon of RO water.

    * 0 ppm
    * pH 6.3

    added Hydroguard

    * 2.5 ml - gallon
    * pH stayed at 6.3
    * 0 ppm

    added Silica Blast

    * 2.5 ml - gallon
    * pH jumped to 9.3???
    * 0 ppm

    added more Silica Blast

    * 2.5 ml - gallon
    * pH jumped to 9.6
    * 20 ppm - 0.4 ec

    added Sweet

    * 15 ml - gallon
    * pH went down to 8.2
    * 420 ppm - 0.62 ec

    added Cal Mag +

    * 2.5 ml - gallon
    * pH went down to 8
    * 530 ppm - 0.78 ec

    finally, Liquid Karma

    * 5 ml - gallon
    * pH went down to 7.5
    * FINAL PPM 600 - 0.88 ec

    After adding these supplements in 1 gallon of 0 ppm/6.3pH water. My final numbers came to 600ppm - 0.88 ec and a pH of 7.5
    Lucas, when the time comes to start experimenting with ebb/flo, how do I actually go about feeding the plants if I decided to use these additives? Would I add flora nova till the ec is .9 and then add the additives till its around 1300 ppm? As far as pH, I use Silica Blast to bring it up =] Thanks again ^^
  • Lucas CannabiNerd Posts: 294
    edited May 2006
    warning long phylosophical post ahead
    Thanks for the reassurance LO

    my self deprecating ways are but an attempt at humility, not everone shares your opinion of me, unfortunately. but I offer myself to be tested in hopes of improving.

    for your entertainment, here is a quote from the Mullah Nasrudin,


    I have disturbed the peace successively in Baghdad, Medina, Beirut and Basra, I caused pandemonium in Damascus, then dropped in at Cairo, where I held the office of chief judge of the city. I will not tell you whom I judged and how I judged, but you may know that I was sought for and hunted all over Egypt for a space of two years. Of course I was far away at the time, travelling in other lands and upon other roads.

    Q: Have these travels taken you to the former Soviet Union?

    A: It is not called for nothing the FORMER Soviet Union.


    and a story from Idries Shah

    There was once a small boy who banged a drum all day and loved every moment of it. He would not be quiet, no matter what anyone else said or did. Various people who called themselves Sufis, and other well-wishers, were called in by neighbors and asked to do something about the child.

    The first so-called Sufi told the boy that he would, if he continued to make so much noise, perforate his eardrums; this reasoning was too advanced for the child, who was neither a scientist nor a scholar. The second told him that drum beating was a sacred activity and should be carried out only on special occasions. The third offered the neighbors plugs for their ears; the fourth gave the boy a book; the fifth gave the neighbors books that described a method of controlling anger through biofeedback; the sixth gave the boy meditation exercises to make him placid and explained that all reality was imagination. Like all placebos, each of these remedies worked for a short while, but none worked for very long.

    Eventually, a real Sufi came along. He looked at the situation, handed the boy a hammer and chisel, and said, "I wonder what is INSIDE the drum?"

    this is similar to my attempt at understanding how roots acquire oxygen, instead of concerning myself with additives designed to solve symptoms caused by lack of oxygen

    what IS inside the drum? NOthing. NOthing is SomeThing.

    using NO additives is more in harmony with enabling the plant to thrive than needing additives to solve symptoms

    here is a Mullah story to that effect, where NObody IS SomeBody
    The Guest of Honor

    The dervish Nasrudin entered a formal reception area and seated himself at the foremost elegant chair. The Chief of the Guard approached and said: "Sir, those places are reserved for guests of honor."

    "Oh, I am more than a mere guest," replied Nasrudin confidently.

    "Oh, so are you a diplomat?"

    "Far more than that!"

    "Really? So you are a minister, perhaps?"

    "No, bigger than that too."

    "Oho! So you must be the King himself, sir," said the Chief sarcastically.

    "Higher than that!"

    "What?! Are you higher than the King?! Nobody is higher than the King in this village!"

    "Now you have it. I Am NObody!" said Nasrudin.

    > Lucas, when the time comes to start experimenting with ebb/flo, how do I actually go about feeding the plants if I decided to use these additives? Would I add flora nova till the ec is .9 and then add the additives till its around 1300 ppm? As far as pH, I use Silica Blast to bring it up =]

    why would you want to use those additives?

    silica seems to be alkaline, so it should be added to the plain water before everything else.

    I suggest you get the NPK and Mg info off all the additives you are using, and plug them into pH's spreadsheet, then post the results here, or if you dont know how to do that, post the label information from each product you are using and I will do the math, unless, hopefully, someone else would like to take a shot and save me the grunt work

    I will then be able to have some clue about how much NPK and Mg your additives contribute to the mix.

    only some of the TDS in your additives counts. The part that contains NPK and Mg.

    the TDS of the additives alone is not enough to tell you what the nutrient value of the additives is. For example, both Sweet and Cal Mag contain epsom salts, which provides Magnesium (Mg). Why are you using those? Flora Nova, unlike Bottanicare nutrients like PBP, is rich in Mg without need for adding more epsom salt.

    And btw, too much epsom salt will kill your plants.

    So, why do you want to use 6 different products, when you only need ONE????

    it can be done, the plants can survive, but why?

    help me understand what makes many people, of which you are only an example, have the belief that 6 products is better than one?

    what does any one of those products do, that proper oxygen and co2 levels cant accomplish without additives? for example, hydroguard is a product designed to treat the symptom of rotting roots, which is caused by lack of oxygen, which is caused by heat and overwatering.

    what if you could solve the heat and overwatering problems, without hydroguard, would you be willing to remove it from your list of ingredients?

    thanks for helping me understand

    I invite you to go into detail on each additive you use and why
  • Indica SativaIndica Sativa Member Posts: 68
    edited May 2006
    I'll get to work on the spread sheet now =] As far as using additives, are you saying that none of the products I listed would benefit my plants in any way? Or any product for that matter? I am just trying to understand... does FNB absolutely, positively have 100% of all ingredients a healthy plant needs?

    p.s... that was probably the best reply I have ever received in a forum ^.^
  • Lucas CannabiNerd Posts: 294
    edited May 2006
    > does FNB absolutely, positively have 100% of all ingredients a healthy plant needs?

    Yes, so does 0-8-16, so does PBP plus Cal Mag. In fact there are even people whose plants are happy with nothing but PBP, to my amazement.. as discussed in the calculating nutrients thread

    Yes, there is absolutely nothing in any of the additives that a plant cannot live without, IF YOU USE FULL strength nutes.

    If you screw with 50% of this and that... youre back to needing additives

    although nutrition contains many subtle elements besides the basic 4, NPK and Mg that I profile, the plants dont actually live on nutrients.

    nutes are just like vitamins, or electrolites, they help the plant build tissue by helping it to transport things it is extracting from air and water.

    Carbon, which comes from air, not nutes, is the main ingredient in plant life, on a gram per gram basis. Hydrogen is one of the other main four elements that make up the body mass of a plant, it is obtained by splitting the water molecule. As if photosynthesis was a form of nuclear fission. Oxygen is also a very high proportion of plant tissue, again from air, not nutes. Nitrogen is the final top four in mass contribution, it does indeed come from nutes. The only one of the top four.

    Now for Magnesium, the metal that catches fire. When sunlight hits the magnesium molecule in the middle of the chlorophyl, it "sparks" the photosynthetic reaction. As if Magnesium was somehow harnessing sunlight, it causes the plant to accumulate carbon. when we later burn the plant, the sparks of sunlight energy that were used to assemble the carbon that built the plant tissue is released as fire :-)

    btw, the hemoglobin molecule, which makes blood red, has the same chemical structure as chlorophyl, with one exception, in Hemoglobin, Iron replaces the Magnesium. the result is that the Iron molecule "oxydizes" and captures Oxygen from the lungs, which is then delivered to other cells by the blood stream.

    In the case of a plant, oxygen is dissolved in water that bathes the roots.. the roots inhale the oxygen, as through the gills of a fish..

    but back to your question
    do the additives have benefits?
    yes, but not if they are misused

    for example PK 13-14 is great stuff, but it is very potent, and needs to be tailored to particular phases of maturation

    the recipes I give as one size fits all, work great, dont need flushing, and produce healthy plants.

    people who tweak their nutes for different stages of growth, if not overdone, also produce perfectly good medicine.

    to me, this has come to imply that the nutes really dont matter as much as we might like. for example, the plant will be happy within a range of nutes, and they will take what they need, as long as there is no single completely missing essential ingredient, such as N, or P or K or Mg..

    not to ramble further, you asked a great question, does a single product have everything, Yes. The plants needs for oxygen, carbon and water are more critical than the need for nutes additives. (as long as you use the recipes I offer at full strength when under full strength light, even on small plants)

    resist the temptation to reinvent the nutrient program for cannabis. Instead, know people who control their plants environment well, get 2 pounds a light, even from a single nutrient with no additives.

  • Indica SativaIndica Sativa Member Posts: 68
    edited May 2006
    Hooray! I pissed my money away =]
  • guest Posts: 24,389
    edited May 2006
    Don't feel bad IS, I have a whole shelf system just for all the snake oils I bought! My Hydro store got me good, they must have smelled fresh blood

    Hey Lucas, my question gets away from the normal pH, ppm and environment issues.

    Would using Fulvic and/or Humic acids have any benifit in a Hydro garden when used in conjuction with 0/8/16 or even 8mls of FNB? Or are they also snake oils?
  • Lucas CannabiNerd Posts: 294
    edited May 2006
    high kisanth

    I honestly dont think any of the additives are "bad" unless they are used in combinations that create overdoses or pH problems.

    I dont think ANY additives are necessary, but otoh, I dont doubt that they can be used to help the grower feel more interactive, without causing harm, and possibly even being helpful to the plants metabolism.

    therefore, Im not going to go as far as to call any additive a snake oil, just unnecessary.

    given the choice that an additive could be good, bad, or neutral, I think they can be used to produce any of the 3 possible results.

    Of course, if you dont use the additive, there is no chance that the bad or neutral result will occur. And if you buy a complete nutrient, many of which now contain Humics, then there is no need to add additional additives.

    otoh, Im sure there are many people who have developed a feel for a combination of ingredients, including humics and or fulvic acids, that works for them in combination with other products, to build a combination of products that meets the needs of the plants, just like a one bottle commercial product can.

    What I most discourage, is the use of additives to remedy problems, that are actually caused by environment, instead of nutrition defficiencies or overdoses.

    One of the most common overused additives is Clearex. It is used to remove excess nutes, after a feel based grower has overdosed their plants with additives like PK 13-14. Unfortunately, I have seen regular and repeated learning curves in people who get their plants so waterlogged from flushing them, that it is no longer possible for the plants to survive. The roots die, the pH drops, the leaves curl, and the grower starts looking for better additives. The real problem in this example, is overwatering, after overfeeding.

    The flushing additive did absolutely nothing but allow the grower to mess with their plants even more often, but the plants dont appreciate being water logged.

    see my drift?

    as to your original question, Im sure you or someone else willing to risk a crop on an experiment, could come up with a recipe that uses humics and fulvic additives, without hurting the plants. I doubt though, that the use of any additive will increase the yield of a garden beyond what could be done without the additives.

  • guest Posts: 24,389
    edited May 2006
    Lucas~ Thanks so much for your contributions. The loss of your most informative threads and discussions at our old site is quite severe. It is great having your counsel once again! Thanks for all your past help.

    Due to members such as yourself the future of C-W is looking better and better everyday and folks will grow better in every way!

    Cybertoke of my very best to ya! :joint3:
    Muggles :pipe:
  • guest Posts: 24,389
    edited May 2006
    Muggles, as usual hit it right on the head. Lucas I have learned more from reading your threads on hydro-feeding than any other form of info. I cannot possibly thank you enough for the invaluable information you have posted. The hours I have spent reading your posts were not only informative, but often entertaining as well. Your sense of humour and light sarcasm along with the information makes very interesting reading. You made me a believer with your FloroNova formula and have saved me a lot of money on supplemental additives! My hydro shop here really misses my wallet I am sure. Keep up your contributions as they are well appreciated. :worthy:
  • guest Posts: 24,389
    edited May 2006
  • a_goodman Posts: 1,313
    edited May 2006
    [CENTER][url=]!!!Be aware of the three headed monster!!!

    General Key to Foliar Symtoms of Mineral Deficiencies in Plants
    also containing Tenative General Key to Foliar Symptoms of Mineral Toxicities in Plants

    Dolphins, eskimos, who cares? It's all a bunch of tree hugging hippie crap.
  • guest Posts: 24,389
    edited May 2006
    Lucas said:
    I did at one time create a complex mathematical formula to predict how much nutes you need to addback for a given res TDS. But rather than recreate it, I invite someone to post it.
    Correct me if I am wrong but if my math is correct the formula would be:

    ((Number of Watts) / (Gallons in reservoir)) X 1.65

    If I am wrong please feel free to correct me but with the numbers you put out above: 1000Watts, 50Gal reservoir, and 33% nute works.

    Thanks for all of the great advice and knowledge LUCAS, most of what I've ever learned was from you bro!
  • Lucas CannabiNerd Posts: 294
    edited May 2006
    thanks for the kind words friends

    hello Agent-Smith

    your figures are accurate, but Im looking for something else

    its involved with discount and markup math

    the markup formula uses the target tds, and a current tds, to calculate the percentage difference, then use that percentage to multiply against the 8ml that produces the target

    so if for example the target is 1300 and the current is 900 with a 50 gallon res it maths out like this

    target/current-1*8*Res Size=how many ml of nutes to add to the res

    1300/900-1*8*50=178 total ml of nutes to add to the res

    phew, you forced me to remember that, thanks

    this formula is much more accurate than a 33% addback. It is based on markup math, and produces a nute dosage that will tend to be slightly too much, the TDS will be overshot

    the inverse formula, using markdown math, produces a more conservative estimate

    it goes like this
    1-(current/target)*8*res size=total ml of nutes to add to res

    what counts is to get enough nutes added back to get up to the target TDS, of 1300-1400

    the two formulas are predicting that to raise TDS 400 points will take between 125 to 172ml of nutes

    once you do it once, it will be the same the next time... you just need to get into the ballpark, or raise TDS in steps..

  • Strawberrycough Ellis Boyd 'Red' Redding Posts: 33
    edited May 2006
    Hi Lucas,

    Thank you for everything that you have ever posted. I have been reading your threads for the last 2 years.

    Question: (for the lucas formula) with the add back are you also adding water? or is it straight micro/bloom.
  • guest Posts: 24,389
    edited May 2006
    Thanks for the response Lucas. :)

    My bottles of FNB don't mention Humics at all, nor do the FNG ... however, I do own FossilFuel (15% humics) and Ruby Fulvic (5% fulvic) both derived from Leonardite.

    I know first hand that the Lucas formula grows perfect plants each time because the NPK Mg and Ca are at adequate levels for almost all if not all strains.

    I was looking for that one non-NPKMgCa product that might enhance a crop. Guess It's time to put some of those snake oils in the collection to use in the way of side by side tests....

    Here's another one for ya if you don't mind.....
    We know that the Lucas formula, 0/8/16 of GH or 8ml/gal FNB, works for DWC and even E&F, but what would you recommnd for a 100% perlite drip system?

    Thanks again Lucas,

    nuggdigger, thanks for the link bro, I just opened it and I'll read it when I get a spare minute. ;)

  • guest Posts: 24,389
    edited May 2006
  • Lucas CannabiNerd Posts: 294
    edited May 2006
    > with the add back are you also adding water?

    good question

    the reservoir should be topped up with water before taking a TDS and pH reading

    Only After the reservoir is full, should you take TDS and pH readings, and add nutes. With the 33% addback approach, you can nute the water before it is added to top up the res, but it wont guarantee that the TDS will get back to 1300, you may still need to add additional nutes..

    for example, some light to res ratios require 100% nuteing of the addback water, in order to achieve 1300TDS

    the nute in the addback water approach, involves mixing nutes in the water that is going to be used to top up the reservoir. The benefit in DWC, is that you dont have to pump out, to dilute the nutes being added to the root zone.

    Do not add pure undilited nutes to a DWC root zone, it will kill roots, and can cause entire plants to suddenly droop and die.

    some warnings
    in Ebb flow it is safe to add pure nutes to a res, but in DWC it is NOT safe to add pure undiluted nutess to the res that has roots in it

    in order to nute a DWC container, it needs to be pumped out into a non root holding container, or at least several gallons worth. Then the nutes get diluted in the pumped out water, before putting the nuted water back into the DWC root zone.

    > We know that the Lucas formula, 0/8/16 of GH or 8ml/gal FNB, works for DWC and even E&F, but what would you recommnd for a 100% perlite drip system?

    another very interesting question
    I would go with DeltaNugz experience

    here is the concept behind feeding, that I think applies equally to ALL growing styles

    0-8-16 in the root zone, which has a TDS of ~1300 is good for all roots

    In EbbFlow, DWC, and constant drip, there is little nutrient accumulation in the root zone. All those systems are essentially constantly bathed in nutes, so the systems are not accumulating nutes the way that happens in a pot of soil.

    This question opens the pandoras box on the topic of "how to water" which I have been trying not to get into, until now

    here goes
    the goal of watering is to provide oxygen as well as nutrients.

    In EbbFlow the oxygen arrives during the ebb cycle, as the pots "breathe". I think of the tropical jungle mist between the grorox as the ideal oxygen absorption environment.

    In DWC the oxygen is provided by airstones, because there is no ebb cycle

    in top drip, if you have an ebb cycle, oxygen arrives during the same "root zone mist" as in ebb flow, or if using constant drip, oxygen will need to be infused by airstones...

    now for the problem, why do folks in dense, slow drying mediums, use less than full strength nutes? The answer is, nutes accumulate in a pot of soil, every time the medium dries out. Especially if full strength nutes are used for every irrigation.

    Soil growers learned early on not to feed daily, instead they feed weekly at full strength, or daily at quarter strength. Or they feed full strength for a while, and as the plants get unhappy, the grower "flushes" the soil.

    Nutes dont get eaten by the plant, they stay in the soil, when the water evaporates, therefore, a soil grower must keep track of the actual TDS in the root zone, as it builds up over time.

    These comments apply to any dense medium, not just soil.

    The reason there is such a strong belief in "flushing" to produce quality end product, is because of the history of soil growing having the problem of nutes accumulations.

    The root zone TDS goal is the same in soil or DWC, but in soil, the irrigation strategy needs to account for nutrients accumulation in the medium.

    So if I was teaching a soil grower how to water, the principles are
    1. use no more water than the plant will consume in 24 hours (if roots stay wet, they use up the oxygen, and no new oxygen will be acquired until the medium dries out enough to breathe)
    2. water with plain water for 2 irrigations, then feed at full strength in the 3rd irrigation, or, use 1/3 strength nutes with Every irrigation.
    3. On the feeding irrigation, allow runoff from the bottom of the pot, so you can test the TDS and pH. IF the TDS of the runoff is higher than 1800 TDS (all TDS values are at .7 conversion), reduce the amount or frequency of adding nutrients in the future waterings.
    4. Flush the medium with plain water IF the runoff goes over 1800.
    5. If pH goes below 5, in the runoff, flush the medium with plain water.
    6. Ideally, the runoff TDS and pH should be ~1300ppm @~5.8pH

    bear in mind that as a pot of medium dries out, the pH drops, and the TDS climbs. The goal is to keep the TDS and pH in the root zone from becoming too strong.

    Flushing is not necessary in DWC or EbbFlow, or any system that has a TDS below 1500 in the root zone.

    OTOH, it is common to see runoff above 2000TDS in pots of medium. They should most definitely be flushed until the runoff is below 1300, before feeding again, and also before harvesting.

  • guest Posts: 24,389
    edited May 2006
    Lucas said:
    0-8-16 in the root zone, which has a TDS of ~1300 is good for all roots
    Hey Lucas, first off thanks for this thread.

    Could you explain to me what is going on? If you use a 0,8,16 in RO water is the TDS 1300 ppm?

    I have been using 0,8,16 formula for years in a bucket ebb/flow system but my meter never reads anywhere near 1300 ppm. My water starts out at 250ppm. No RO system. When I add the nutes my reading is 1000 ppm more or less. As the res level drops I add back plain water to the original volume and take a reading. When the ppm falls to 800 I change the solution. This system has worked well for me I just don't understand the TDS readings.

  • Lucas CannabiNerd Posts: 294
    edited May 2006
    hello Kurious

    there are 4 different types of meters that measure nutrient concentration, two are EC meters and two are TDS meters

    of the 2 types of EC meters, (electrical conductivity), one displays with decimal places, the other without

    for example
    EC 2.0 and EC 2000 are the same

    TDS meters come in 2 types, .5 and .7 conversion.

    You seem to have a .5 conversion TDS meter

    TDS meters take the electrical conductivity value that is measured internally by the meter (EC), but then multiplies the EC by a factor, either .5 or .7

    so for example,
    2000EC * .7= 1400ppm but also
    2000EC * .5= 1000ppm

    TDS is a strange beast and does not react logically, as you have found

    for example 0-8-16 should read 1000ppm on .5 conversion meter, in RO water, but strangely, if you start with 250ppm water, and add the nutes, it wont necessarily come out to 1250, as you have noticed.

    the reason I think this happens is that some of the TDS in the water gets neutralized by the nutes.

    for example, much of the TDS in water is calcium, which is of very high pH. When nutes, of low pH are mixed in, some of the low and high values cancel each other out... this is sometimes called nute lockout and is the cause of some of the sediment in a res.

    as far as the term TDS (total dissolved solids), in contrast to the term PPM (parts per million), they are the same thing stated in different words

    here is an example of how the terms interact

    An EC of 2000 corresponds to a TDS reading of 1400 PPM on a .7 conversion meter.

    imho, .7 conversion is the primary hydroponic conversion factor, but many people own meters with .5 conversion, therefore, you MUST know your conversion, to understand my TDS numbers, which are all .7 values unless stated otherwise

    in practical terms though, what you are doing is correct, and works fine, as you know

    the gardner should mix nutes at the known recipe rate, then take a meter reading. WHATEVER that number is, regardless if its 1000, 1400, or any other number, THAT is the TDS of YOUR nutes in Your water, on Your meter.

    As long as you dont change water or meters, keep using the baseline number you get as the target to go back to with nute additions

    Im loving these questions! this is turning into a very complete archive of my beliefs

    none of these ideas are original, Ive just spent a lot of time reading and learning from others

    thanks to all my mentors and friends
  • guest Posts: 24,389
    edited May 2006
    Lucas, thanks for your reply. You have answered some of the nagging questions that have been puzzeling me for a while. I knew what I was doing works but did not understand why I wasn't coming up with the same numbers as others. Thanks again.

  • guest Posts: 24,389
    edited May 2006
    Lucas, is it ok to simply raise the tds of an 0-5-10 rezup to the target tds of 0-8-16 when flowering is initiated, rather than dumping the rez of 0-5-10 at the end of flowering and mixing up a fresh rez of 0-8-16?

    in other words is it ok to raise the tds of the veg rez rather than dumping it and mixingup a fresh batch of flower nutes?

  • Lucas CannabiNerd Posts: 294
    edited May 2006
    > is it ok to simply raise the tds of an 0-5-10 rezup to the target tds of 0-8-16 when flowering is initiated, rather than dumping the rez of 0-5-10

    yes, if you are vegging in 0-5-10, you can certainly just add more nutes and keep going, by raising the TDS.

    imvho, there is no need to dump the veg res

    Im glad you asked about that, because Ive been meaning to talk a bit about vegetative nutes.
    btw, before I blaze ahead, I dont recommend 0-5-10 as a veg formula actually, I only recommend it as a low light formula..

    now lets talk about vegging

    if newly rooted clones are transplanted into containers that are going to veg under fluoros, that is a sort of weak light situation, and using weak nutes makes sense, ~1000 ppm

    but after the first week or two of fluoros, if the plants move to strong light, HPS light, or MH light, but with big lamps, you know, not fluoros, what is referred to as HID lighting.. then I want them to see full strength nutes.. 0-8-16.. ~13-1400ppm

    now to the question of vegetative formulas
    I find the use of FloraNovaGrow definitely kicks the vegging plants into greener, but also stretchier gear. In fact, vegging with FNGrow, the stalks turn into big hollow things that look like celery.. whereas when vegging with FNBloom, as I have always advocated in the past, vegging with bloom nutes, produces much more solid stems

    sidenote, Clarke claims there is some belief that drug cultivars have hollow stems. I dont know if this is true, but I do know that higher doses of Nitrogen than the bloom recipe I know so well, produces hollow stems in plants that did not have them before..

    anyway, back to the veg nute thang

    I think vegging in FloraNovaGrow instead of FNBloom has some positive effects on kick starting the plants, so I devised an experiment..

    a bubbler reservoir was mixed with FNGrow, and plants were vegged in it for a week, then, instead of dumping, when the light was flipped, all nute additions were FloraNovaBloom from then on.

    so in this case the grow nutes stayed in the res, after veg ended, but only bloom nutes were added to the res when addbacks were made

    this totally unreplicated experiment produced one of the highest yields that gardener has reported.. 1.75lbs per 1k... nothing outrageous, but, the cola size was huge!.. twice as fat as usually seen when veg is done with a low Nitrogen, bloom style nute

    what Im driving at is the idea of feeding the stretch that Mr. Highway mentioned in the past.. the idea of nitrogen loading the initial days of 12/12.. I think he was on to something..

    point of the story, even in this scenario, a res with Grow nutes during veg, not just weak bloom nutes, was not dumped, the Bloom nutes were simply added to the res as the bloom cycle went along consuming TDS..

    so to your original, and insightful question, can one simply keep adding bloom nutes to a vegetative res, once the light is flipped, without dumping the veg res,,, my opinion is YES!

  • guest Posts: 24,389
    edited May 2006
    So Lucas you are saying that you don't have to change the reservoir water at all from the very start of veg to the very end of bloom as long as you just use the addback formula? If so, that would be a serious help for people who use extremely big reservoirs. I would have liked to have that with my last grow and it was only a 20gal res. :D
  • mace Senior Member Posts: 296
    edited June 2006
    I think one reason to dumpt the res between veg and flower if 0-5-10 was used is the accumulation of pH down in the nutes. 0-5-10 will need more pH down than 0-8-16 to lower the pH. After the veg, the grower might have added pH down a few times to correct the pH.

    Ps: Good to see you back in action Lucas :)
  • Carpet Muncher Senior Member Posts: 558
    edited June 2006
    mace, i've never had a time.. other when i added snoils.. snake oils.. when i needed to add 'down'.. and then i used something else because i didn't have any.. what is your starting ph?
  • mace Senior Member Posts: 296
    edited June 2006
    Howdy CM, you're right, with RO, no PH down should be nessecary, with tap, its a different story.
    My tap water pH would start at 7, after bubbling for a day it was 7.8 (without nutes).
Sign In or Register to comment.