hElP Please. PPMs and the lucas formula.

mmkay well i'm pretty sure i know how to figure the lucas formula. i arez no dumby thar. the ppms is what is getting me. do i absolutely HAVE to have a PPM meter to figure the lucas formula ppms each day?? ORRR can i figure it out with pen pad and calculator??

i'm using a very basic 5 gallon bucket, filled 3 gallons which sits about 3ish inches below my 4 1/2inch length net pot....

sensi grow ab for vegging. basic vegg. flower will be different but getting the ppms down BEFORE flower (in about 2 weeks give er take) to make the flower job more efficient.

ANY help AT ALL would be great.

First off, if you're using Lucas formula, read this: Ask Lucas. It's awesome.

But for a quick answer, yes, you do want a TDS meter. I didn't have one for the early stages of my grow and I wish I had. Same goes for a pH pen.

First off, if you're using Lucas formula, read this: Ask Lucas. It's awesome.

But for a quick answer, yes, you do want a TDS meter. I didn't have one for the early stages of my grow and I wish I had. Same goes for a pH pen.

picked up a Hanna TDS today. 38$ at the local hydro shop. whatev. i suppose as long as i can get the right amount nutes goin. thanx for the info. BTW my ppm is at 263...
thanx again.

Good move, your plants will love you for it. Get those PPMs up to at least 1000 unless the plants are still under about 6-8".

(Also, I don't have a Hanna but my TDS meter only shows 3 digits. So anything over 999 displays as ###x10. Make sure you're really at 262, not 2620!)

the plants are at about 8-9" now....i added about 5 mL of solution, that immediately brought the rez up to 730....but 1000?? :S
yish i was kind of worried about 730 ... but it has been overnight now and even only at 730 the change in greenness is evident. i think i'll take your advice and bump it a little more.

i did a little water test between tap, arrowhead, and dasani.
dasani actually chimed in at about 20ppm and a PH of 6.0
far better than the 160ppm and 7+ pH for tap water.
if i use the dasani which is down to 20ppm would eat be intelligent to compensate for the other 150ppm off the tap water?? would that ultimately burn out the plant?? i read i probably would need cal/mag with more RO'd type of water?? any input???

Dasani is reverse osmosis, or "RO" water, which is exactly what the Lucas formula is designed for. Although, 160ppm isn't bad. My tap water is 120-130ppm, pH 7.0 and it's fine. If I were you I'd use the tap water. If you do a whole grow with Dasani you might as well be buying your bud at street price!

Once the plants have a good root system you'll want to keep the TDS around 1200ppm, 1400 max, in whatever water you use. You shouldn't need cal/mag with Lucas, in theory... I've never needed it.

If you'll look at my grow, I didn't use nutes on my first set of clones until they were bigger. They did NOT look healthy until they were getting full strength nutes. My second set of clones got full nutes right away, because they were decently rooted already. No pics of them yet but I can tell you, they're happy

mmmmkay soo riddle me this.
if i am at 730 right now and need to be at what 1200. (the root system is large enough to call it a "ball" tangled in my air lines)
i would do this right...
1-(Cppm/Tppm) * 8 * 3 (my res cap)

so we get 1-(730/1200) * 8 * 3 = 38.6mL ?????? i think i'm doing it wrong....

Rather than complicate things, I'd just mix up a batch of full strength (1200ppm, pH 5.3 or so) and use that to top of your res. Your plants will be ok while you gradually raise the ppm's each time you top off.

Lucas's method is to add plain water to fill the res, then add nutes to bring the ppm's up and the pH down (unmixed nutes are very low pH). But I like to skip all the math and just wing it.

hmmm, very stoney thinking indeed. i like that.
i'll give it a try tonight after work and let you know by morning the results with pics.
last few days of a vegg
very exciting.

my tds pen somehow got water up inside the display...somehow, i never dropped it in there nor did i put it too far, anyhow. i let it sit out to dry and now it works. i have been adding a solution mixed at 1100. haha
ya waitwtf is right also. i thought maybe my tds stick had malfunctioned because of the 1k ppms. it does the same. "x10" effect your stick does. right after it hit "x10" or 1k it stopped displaying... it was strange. anyhow though thanx for all the input on this. i would have been at a complete loss for real man.

mmmmkay soo riddle me this.
if i am at 730 right now and need to be at what 1200. (the root system is large enough to call it a "ball" tangled in my air lines)
i would do this right...
1-(Cppm/Tppm) * 8 * 3 (my res cap)

so we get 1-(730/1200) * 8 * 3 = 38.6mL ?????? i think i'm doing it wrong....

Actually you would have to add 9.6ml of micro and 19.2ml of bloom.

I can send you a spread sheet with the formulas built in. you just need to input the rez size, target ppm and current ppm. if under floro you would change the field for 8ml to 4ml to reflect the strength you are using.

in your formula you did not account for the difference in current and target ppm. the formula is actually the difference in you current ppm divided by the target. If you look closely at lucas' instructions, you will notice that the first math example is to get the difference in ppm.

In your case, 470 (difference between target and current) divided by 1200(target ppm) = .4

SO you would: .4*8(ml)*3(rez cap)
equals:
9.6ml Micro
19.2ml Bloom

Hope that helped out

Edited by scrogger, 01 May 2011 - 03:01 AM.
math correction. I was off by .2ml

:eek::eek::eek::eek:

Actually you would have to add 9.6ml of micro and 19.2ml of bloom.

I can send you a spread sheet with the formulas built in. you just need to input the rez size, target ppm and current ppm. if under floro you would change the field for 8ml to 4ml to reflect the strength you are using.

in your formula you did not account for the difference in current and target ppm. the formula is actually the difference in you current ppm divided by the target. If you look closely at lucas' instructions, you will notice that the first math example is to get the difference in ppm.

In your case, 470 (difference between target and current) divided by 1200(target ppm) = .4

SO you would: .4*8(ml)*3(rez cap)
equals:
9.6ml Micro
19.2ml Bloom



Hope that helped out

i used to be good at this stuff dude. not sure if i'm stoned or retarded right now, but i can figure the ppms. my personal is healthier than ever. but i'm wondering which nutes i'm missing.....


therefore... in my case .... what is *8(ml) ... ml of what??...

n-p-k ratio. grow-micro-bloom

so for micro, which would be between "grow' and "bloom" would be 8 correct?? then bloom would be multiply by 16??

i have ed. rosenthals/tommy chong mj growers guide and i still haven't been able to figure this whole dilliy out.

for some reason my noodle is stretching quite sativaish to figure this riddle out

my ppms are right on the money right now. but i am wondering if i add a dash or two more of a one over the other of a two part fert. if it will benefit the plant intended to do so (as long as i can figure out this damned formujula) or burn the crap out of it because i didn't mix as intended by the manufacturer.

common sense tells me if i mix what the plant tells me she wants, then she'll be happy. but the fert man says mix another way... which is right???


and to be clear do i multiply by 8 for a micro period or 16 for a bloom period???

:eek::eek::eek::eek:

i used to be good at this stuff dude. not sure if i'm stoned or retarded right now, but i can figure the ppms. my personal is healthier than ever. but i'm wondering which nutes i'm missing.....


therefore... in my case .... what is *8(ml) ... ml of what??...

n-p-k ratio. grow-micro-bloom

so for micro, which would be between "grow' and "bloom" would be 8 correct?? then bloom would be multiply by 16??

i have ed. rosenthals/tommy chong mj growers guide and i still haven't been able to figure this whole dilliy out.

for some reason my noodle is stretching quite sativaish to figure this riddle out

my ppms are right on the money right now. but i am wondering if i add a dash or two more of a one over the other of a two part fert. if it will benefit the plant intended to do so (as long as i can figure out this damned formujula) or burn the crap out of it because i didn't mix as intended by the manufacturer.

common sense tells me if i mix what the plant tells me she wants, then she'll be happy. but the fert man says mix another way... which is right???


and to be clear do i multiply by 8 for a micro period or 16 for a bloom period???

18 24 16 is the npk for miracle grow plant food.

so according to ed rosenthal, i am the turning point from vegg to bloom. therefore i need more phosphates (p) at this point because if i get more potash(k) it won't be able to "metabolize" the (k) with the nute (p) first.

so i am wondering i use a bit of this "miracle grow" stuff in moderation per PPMs measuered by TDS (hanna) for a week before more K (potash) if it will help with better bigger buds.

not to question mr. rosenthal but according to him if we purchase a "multi 'on-off'" light switch we should interrupt the dark light cycle for about 10 minutes each "night"

does anyone have any evidence of this being beneficial?
seems as if ed has a pH.d in this shit so it should be correct but i'm wondering more on the "average joe" level if it goes well.

:eek::eek::eek::eek:

i used to be good at this stuff dude. not sure if i'm stoned or retarded right now, but i can figure the ppms. my personal is healthier than ever. but i'm wondering which nutes i'm missing.....


therefore... in my case .... what is *8(ml) ... ml of what??...

n-p-k ratio. grow-micro-bloom

so for micro, which would be between "grow' and "bloom" would be 8 correct?? then bloom would be multiply by 16??

i have ed. rosenthals/tommy chong mj growers guide and i still haven't been able to figure this whole dilliy out.

for some reason my noodle is stretching quite sativaish to figure this riddle out

my ppms are right on the money right now. but i am wondering if i add a dash or two more of a one over the other of a two part fert. if it will benefit the plant intended to do so (as long as i can figure out this damned formujula) or burn the crap out of it because i didn't mix as intended by the manufacturer.

common sense tells me if i mix what the plant tells me she wants, then she'll be happy. but the fert man says mix another way... which is right???


and to be clear do i multiply by 8 for a micro period or 16 for a bloom period???

If you're using the lucas method, then you are using 2 parts (micro & bloom) of a 3 part system. Note you are not adding Grow, only micro and bloom, the whole time.

*8 refers to 8ml of micro. to get the figure for the bloom, just double the amount of micro you need to add back to the rez. the lucas method is 0-8-16 (0 grow-8 micro-16 bloom). so you really only need to figure how much micro to put in, then double that amount for bloom. super easy, man.

Adding more volume of other nutes, or even the same will do nothing. beneficial. The plant will take up what specific nutrient it needs, when it needs it, if you are growing in DWC.

Here is a visual breakdown of info needed to use the lucas formula for rez management:

Note there is a typo in the sheet. where it reads # ML MICRO it is the title for the NUMBER FO ML OF EITHER MICRO OR BLOOM. Since i only use the formula to get my add back for micro, i titled it MICRO. The import info is the number in the column next to it.

Hope this helps, make it easier to remember and use.

Sorry that link was to an older version. Here is the updated (not really.... like march 2010 lol) spreadsheet....

Super's Lucas Addback Calculator

Edited by superusa, 02 May 2011 - 12:51 AM.
link was older version

I MADE THIS CALCULATOR FOR JUST THIS SCENARIO. I USE IT TO CALCULATE EXACTLY HOW MUCH TO ADD BACK TO GET TO MY TARGET PPM. IT IS DEAD ON ACCURATE.

Super's addback calculator

Same as i just posted. BUT....

You are using the formula incorrectly, if you are vegging under a HID light. Ask Lucas himself. Many people make this mistake. I see it in his asklucas thread soo much.

QUOTE FROM ASK LUCAS @ CANNABIS WORLD:
"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.."

If you veggin under CFL or other full spectrum floro, you would use half strength. If you Veg under HID (HPS or MH), you use 0-8-16.

Using 0-4-8/0-5-10 for veg will work, as you know, but it is not advised to get the most out the method.

I only mention this as you have your veg cycle, listed in your calculator, as 0-4-8/0-5-10. Like I said, if you are veggin under floro or non HID light, you are all good.

Here is a link to ask lucas:
Ask Lucas - Cannabis-World
There are links to a printable version as well, for future reference if you need it.

Same as i just posted. BUT....

You are using the formula incorrectly, if you are vegging under a HID light. Ask Lucas himself. Many people make this mistake. I see it in his asklucas thread soo much.

QUOTE FROM ASK LUCAS @ CANNABIS WORLD:
"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.."

If you veggin under CFL or other full spectrum floro, you would use half strength. If you Veg under HID (HPS or MH), you use 0-8-16.

Using 0-4-8/0-5-10 for veg will work, as you know, but it is not advised to get the most out the method.

I only mention this as you have your veg cycle, listed in your calculator, as 0-4-8/0-5-10. Like I said, if you are veggin under floro or non HID light, you are all good.

Here is a link to ask lucas:
Ask Lucas - Cannabis-World
There are links to a printable version as well, for future reference if you need it.

I am aware of that. I actually just cut-n-pasted that lucas blurb from another thread. I personally don't grow using that method anyway, i grow by the EC movement... much easier to determine what the plant needs nutes wise..

DO you add back just water or full strength nutes and water? Curious to know... I add back with full strength nutes and water, so the plant can take up what it needs, when it needs it. no guessing game. I prefer to let the plant feed on what it needs when it needs it. That's why i like DWC and the lucas formula.

DO you add back just water or full strength nutes and water? Curious to know... I add back with full strength nutes and water, so the plant can take up what it needs, when it needs it. no guessing game. I prefer to let the plant feed on what it needs when it needs it. That's why i like DWC and the lucas formula.

Hmmm... well that depends on the situation. I grow according to EC movements. So for example, lets say i mix up my res in my RDWC to 1000ppm@.7 conversion.... then i come back a few days later and the water level has dropped and i whip out my ec/tds meter and check it and it is at 800ppm.... then I would raise my ppms above 1000, since this means that the plant was drinking nutrients faster than water. i would add water a nd nutes back to my res to fill it and set the nutes at say 1100 ppm and repeat. If the EC rose instead of dropped as the level in the res decreased then I would know that I need to dilute the nutes more since the plant is consumung the water faster than the nutrients (which is why the remaining nutes are building up in the water and becoming more concentrated.... thus raising EC/TDs/PPM). This is how i determine what strength to use the nutes at.... not some blind number that somebody gives me. That is what that spreadsheet does.... tells you exactly how much nutes to add back to get to your TARGET ppm.

* Edit: My target ppm is usually wherever the EC/TDS/PPM reading stays the same/flat over a couple of days minus 50 to 100 ppm to get a small upward swing in pH movement

Edited by superusa, 03 May 2011 - 12:43 AM.
Correct a typo and add some extra info