What is Lucas Formula?

[Deltanugz]

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[Deltanugz]

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[Ziggy]

Thank you Deltanugz, I have a mentor teaching me how to do Vertical SCROG. and he uses the Lucas Formula this is my first grow around with Scrog.


Peace

[hydrorascal]

Using GH Micro and Bloom, aka Lucas formula works great. Remember... plants have been surviving for centuries in dirt without all the 'needed' elements.

TDS or ppm's are important BUT... if the res PH is not in the proper range of 5.3 to 6.2, plants will not thrive dispite any efforts.

If I were given a choice of only having one meter it would be a PH meter. A nute solution TDS can be adjusted by watching the plants. PH is much more vital to plant life.

[ihaveworms]

thx delta.. and snap ... great info..

worms

[mace]

1. Top off the reservoir daily using a pH corrected water solution as required to maintain full reservoir level. After adding back an amount of water equal to the amount of your reservoir capacity you should change the reservoir and put in fresh solution.
2. Top off the reservoir daily using a pH corrected 100% strength nutrient solution as required to maintain full reservoir level. Continue to use this nutrient solution without dumping the tank unless the PPM rises above acceptable levels.

That part is not correct, this info is probably from OG's growfaq.

Its either topping off till 100% addback is reached and then changing the res with fresh nutes

or

constantly topping with 1/3 strength addback.

peace,

mace

[Deltanugz]

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[Strawberrycough]

do you have to have RO water? let say your current tap water is 100 ppm can you you just add 1350+100 = 1450 as your target ppm?

[mace]

Tap water contains calcium, which will raise the pH towards 8ish when air is bubbled trough (and that you will need to do) cause the CO2 from the air is reacting with it. This process takes time, ime at least 12-24 hours.
If your water contains a lot of calcium, you will need a shitload of pH down, till you poison your plants cause you tried to keep the pH in range.

So, the question is, whats your pH after bubbling a gallon of 0-8-16 for 24 hours?

On the other hand, FloraNova Bloom is the same as 0-8-16, but its pH is buffered for tap water that contains calcium ;)

gl,

mace

[hydrorascal]

strawberry... with your tap of 100ppm you should be fine

[BlueCelisWhite1]

Whats the 0~4~8 ratio?

Expected PPM levels:

At .5 conversion:
0-4-8 = 473ppm
0-5-10 = 592ppm
0-8-16 = 947ppm

At .7 conversion:
0-4-8 = 663ppm
0-5-10 = 829ppm
0-8-16 = 1326ppm

Also what is actually better for the plants as far as addbacks? 1/3 strength or fill with reg water until origanal gal capacity is reached?

[hydrorascal]

0-8-16 with a .7 meter = 1320ppm

[BlueCelisWhite1]

Need so thought from you guys for a little reassurance on what Im doing.

I set up 2 new tubblers yesterday with the following:

2 plants per tub in 25 gals of 1/4 strength lucas form.

My starting RO water was Ph of 6.1 and ppm of 25. After adding 1/4 strength lucas for with GH nutes my ph was @ 5.6 and ppm @ 356

Today the tubs are @ ph of 5.9 and ppm of 378

Do you guys think I should try lowering ph with ph down or give it a day or so more to see if ph stabilizes?

Some other questions just for clarification if you will.

As far as PH if I was running lucas as full strength 0-5-10 my ph would be lower than my starting ph with 1/4 strength right? becuase of more nute concentration? Or no?

Also how should I maintain my ppm for these new cuts? If the ppm starts rising should I start adding more plain water to them and at what point should I start adding water with the rising ppm if it does rise?

So if my starting ppm was 356 and today they rose 20 or so points when should I add more straight water so my ppms dont rise to much?

Sorry for the redundancy!

thx for the help!

[hydrorascal]

Great points of question ! Asking such almost 100% insures you many happy harvests.

25 gallons per 2 plants is lots of res room, good choice.

DO NOT chase PH. A properly running res will swing up to ~6.1/6.3 and drift back down to the mid 5's. Yes your starting res PH would have been lower with 0-5-10 than with the 0-1.25-2.5 you are using. I would ask why you started soo low ? 0-5-10 works great for plants with roots popping..which is when they should start feeding.

I would dump the res and refill it with 0-5-10 balanced to start about 5.3

2 plants that shift in 24 hours that large a res are feeding very very well. By the way they are chowing down on your baby food nute mix.. they are more than ready for 0-5-10.

Topping your res will sure help keep your TDS in line. As they grow the res level will drop more each day... just keep it within a 1/4" of the bottom of the pots...

Your starting them at 1/4 strength is a common misconception, imo. 0-5-10 with a proper PH and temperature has been proven to be a nute formula that newly rooted plants love.

[BlueCelisWhite1]

oops actually i started them at 1/2 strength. Since the res is only a day old could I just add the right amount of micro and bloom to bring it up to 0-5-10? And if so is it going to screw anyhting up if I have a actice res with mixed nutes like i do to add the micro first and then bloom like I do when mixing?

Thx a bunch Hydro!

[hydrorascal]

BCW.... half strength = 0-2.5-5 just so we know where we are. At day 1+ of a res adding 2.5ml of Micro and 5ml of Bloom per res gallon shouldnt be any issue.

Prior to doing so I would suggest mixing a gallon in the same way using your water source just to be safe. To be clear... mix a half strength as you did with whatever PH adjuster first, then add the necessary nutes to get to a 0-5-10.

Good point on the add back procedure to.... with General Hydroponics always add the Micro first... prior to anything else going in the res... the exception being PH adjusting the water to insure a starting point of around 5.3

[BlueCelisWhite1]

Hey that brings me to another question : )

On phing the water before hand. Why do we ph before adding nutes if we are not entirely sure how far down nutes at say 0-5-10 or -0-8-16 will bring ph down in itself. Should we know our water source more? Since my RO syatem is fairly new to me and I havnt really worked with it enough to know how it reacts in growing conditions persay. Should I be doing some research on the line of take a gal. of straight RO nuting it to 0-5-10,0-8-16 and documenting the ph?

And then knowing say 0-8-16 brings my RO water down from 6.1 to say 5.4 or somehting then I know to ph my water and bring it down a point or two?

Hate asking the newbie questions but seems the reasurrance from those with more experience and grows under their belt helps is the learning process!

Thx man!

[hydrorascal]

Questions are the key to learning. Questions without regard to the smucks who snicker while only wishing they had the wherewithall to ask themselves.

The easiest way I have found is to mix a gallon with whatever water source to be used normally. 0-5-10 or 0-8-16 ... the method is the same. Mix one gallon, measure the PH and add usually PH down 1ml at a time until you have about 5.3. That one ya can dump on the nearest outdoor plant.

Fresh gallon of water, add the indicated amount of PH down. Let it set a few minutes after mixing. Add your Micro, mix and add your Bloom. Assuming the mix comes in at about 5.3 you now have a 'known' mix.

I say known due to the fact that most cities change their water chemical composition 2 or 3 times a year.

If your RO plus nutes comes in at 5.4.. Id just go with that... your plants are gonna drive it up rapidly anyway....

[BlueCelisWhite1]

Out of curiosity what exactly makes the rez swing upwards and then drift back down?

Thx again for all the info Hydro! You da man brother!

[GrowGreen]

Several things cause this... most likely with a newly mixed res, it

[BlueCelisWhite1]

excellent thx for the info GG

[Lucas]

good questions BlueCelisWhite1

> Also what is actually better for the plants as far as addbacks? 1/3 strength or fill with reg water until origanal gal capacity is reached?

the plants grow better with nutes addbacks than with just water addbacks to 100% refil

> Do you guys think I should try lowering ph with ph down or give it a day or so more to see if ph stabilizes?

no
your nutes are too weak, assuming the plants are under HID light, you should use full strength 0-8-16, which will drive your pH much lower.. you will probably need a little pH UP

> So if my starting ppm was 356 and today they rose 20 or so points when should I add more straight water so my ppms dont rise to much?

your PPM's should be checked when you have a full reservoir... if the plants consume water, and the TDS rises, you should add water, then measure the TDS

dont go by the TDS of a res that has lost water and has not been topped up..

and dont pH adjust the addback water.. let the refilled res tell you its combined TDS and pH before you adjust anything

hth
Lucas

[BlueCelisWhite1]

So ideally I want to try and stay at my target ppms as much as possible?

So Im running half strength right now. Water level really hasnt dropped much from my fill line I made on the inside of the tubs. Since the solution is only 2 days old and the tds hasnt move either way much is it possible to add nutes without dumping and starting fresh? If so can I just add 62.5 ML of micro and 125 of bloom to bring it close to 0~5~10? If so how should I apply it? Directly pour micro in tubs let it mix with 1/4 strength solution and them bloom? Or should I premix it all in 1 gal. of water and then dump into rez?

"your PPM's should be checked when you have a full reservoir... if the plants consume water, and the TDS rises, you should add water, then measure the TDS"

And I know the plants are consuming more water becuase my TDS will be greater and possible on visual inspection water level has dropped from fill line? So I would want to refill with straight water and then check ppm hoping to bring the raised ppm back down to the target?

Say after time the same readings keep showing that plants are taking in more water than nutes whats the point at which we stop trying to lower ppm back down to starting target ppm and actually bring the ppm down below starting bt adding more water?


Also when using Lucas form. is there any sort of calculations that show a margin error either way? So for instance @ .5 conversion true lucas is 0-5-10 = 592ppm whats the give or take margin on ppms if any?

Thx!

By the way great answers! : )

[Lucas]

> is it possible to add nutes without dumping and starting fresh?

yes, you can add nutes to bring TDS up to target of about 1300ppm@.7 conversion

> If so can I just add 62.5 ML of micro and 125 of bloom to bring it close to 0~5~10? If so how should I apply it? Directly pour micro in tubs let it mix with 1/4 strength solution and them bloom? Or should I premix it all in 1 gal. of water and then dump into rez?

adding raw nutes to a root zone is a problem. it can kill the roots, so you have to dilute what you are adding, but your res is full, so you cant mix into new 1 gallon bottles..

instead, you should pump out your reservoir into another container, and do all your nutes additions there, then pump the corrected nutes back into the root zone

(or lift the lid off your current bubbler, removing the plants from the res... a spare tub is handy for this approach, but its not practical once the plants get big)

when andjusting pH UPWARDs it should be done BEFORE nutes are added.. so you should follow hydrorascals advice and mix a test batch, so you know how much pH UP you need per gallon

when adjusting pH DOWNWARDs it should be done AFTER nutes are in the water

I also agree with hydrorascal that using quarter or half strength nutes is a common misconception.. IF the plants have strong light, not fluoros, they can handle 0-8-16 without altering the formula.

as to TDS readings, they are all derived from EC, mathematically.. 2000 EC, sometimes reported as 2.0EC is the same as 1000ppm@.5

the .7 conversion is problematic.. some meters use .667 which is close, but not exactly .7...

what really matters is that you note the meter value your personal tool is reporting, for a properly measured 0-8-16 mix. From then on, whatever that value is on your meter, is YOUR target tds

hth
Lucas

[hydrorascal]

A very simplistic view is to consider your res a buffet line for your plants. PH is the ticket that allows you full access to the buffet. IF your PH is in the correct range that is.

A proper TDS load is just a fully loaded buffet. Adding back only refills those areas that the plants have already fed on allowing them to have more if they care to.

Taking that same example, it shows the value of proper res temps too. At a proper temp one will spend more time at a buffet than if its too hot/cold.

If you have a powerhead in the res (another advantage) and use a transmission funnel....the loong barreled one... Micro and Bloom can be added directly to the res by having those enter at the bottom of the res. Done so many many times with zero negative effects. If you only have a short funnel add a piece of tubing to it....

I personally do not premix an addback of Micro and Bloom. Just add one at a time, Micro ALWAYS first.

Keep your PH meter calibrated too. A PH meter out of calibration is a very bad thing to use. I learned that by using an uncalibrated meter that when finally checked was almost a full point low. Dry 4.0 and 7.0 caps are frequently available on ebay. Each capsule makes 100ml.

Keep up with the questions... I can almost see your plants jumping for joy !!

[BlueCelisWhite1]

Thx guys. Alot of this is refresher and enlightment for me. I have had successful grows in hydro and using lucas but Im to the point now that I want as much understanding of everyhting involved with my plants if you know what I mean.

Ya I think things are going to go real well. My main concern right now is getting myrez up to full power instead of half strength like it is now. Since I only really planned to veg. for 8 more days at the most Im debating on whether to just run what I have now for the remaining 8 days even being half strength. Or should I bump up to full for the 8 remaing veg days?

Cuts are not very tall and normally I like to veg them pretty big for bush style. But I think I will flower them much earlier this time. Im hoping in the next eight days they get to about 7-10 inches tall. Right now they are only 4-5 inches. I might be asking for alot only vegging 8 more days but Ive seen some pretty hardy growth in tubs so maybe.

I dont know why I started at 1/2 strength this time around. My last run of Calizahr I went right in full strength lucas with no probs. I guess Im feeling a tad rusty since I shut down for a bit and now trying to pick up again. Its not that I forgot its just the reassurance does wonders for stresses that can be involved ya know.

I will snap some pics this weekend.

Eeven my soil plants are coming along nicely. They were being baby sat while I had my surgery and they were in desperate need of repotting and food. They are happy f'ers now!

Ya you can be sure I will be throwing more questions out. Im pretty much documenting eveything now. I have a spread sheet going with all my water info ph, ppm @ what temps ect..

I love it!

thx for the help!

Its nice knowing a couple cats like yourselfs are right here when we need ya. You knowledge is priceless

thx dudes!