Lucas Formula and Method(s): Step by Step

[Mr_Spliff]

Yeah this Lucas thing is all about ratios, not some formula, like what the fuck is a formula? I know what a ratio is, but formula sounds all spiffy. When I look at the ratios on the three bottles you can easily see that the floragrow definitely throws the ratio off once all mixed up.

I recently saw someone use this ratio for Coco I think, 0-6-9, I think it was RezDog in his forum about "The Recipe" I suggest you look for it if your that interested. Im glad I did.

 

[delta9nxs]

again

again

This is for all those just starting out in our little hobby. You old farts can just grit your teeth and suffer!

The lucas formula is nothing more than a ratio. One part to two parts with flora series. Plus suggestions for feeding strength. It is the “suggestions for feeding” that are the cause of all the confusion. The same elemental makeup or ratio can be achieved with other nutrients, such as Hydro-Soil has demonstrated. As we all use different growing methods and different light setups we should not use the same strength. While lucas uses ebb and flo with strong hid lighting and 8/16 (1/2), someone else is hand watering pots of coco coir with flourescents. Maybe they should try 5/10 (1/2). They can use the same ratio but not the same strength. The 8/16 strength is fine for most active hydroponic systems using strong lights, but will probably burn the hell out of that little clone being hand watered under that cfl. I have been told by some aeroponic and dwc enthusiast that 8/16 is a little too strong for their application. It will be way too strong for hempy buckets.

Every medium has a different cec (cation exchange capacity) turface, coco, and vermiculite all have rather high cecs, whereas perlite has a very low one. Cec refers to the medias ability to retain nutrients. Not good or bad, just different. Every choice of media will be different. Even using no media is a choice and will make unique strength demands depending on style and lighting. The ratio, however, remains the same.

Lucas and many others have experimented over the years and have developed a pretty good idea of what the specific elemental nutrient needs of cannabis are. There are a lot of slightly different opinions but they are almost all in the same ballpark. The lucas formula, using flora series at the 8/16 strength, meets those needs.

I have grown using many different styles over the years, ebb and flo, nft, drip, dwc, bio buckets, and passive. hempy style with the internal reservoir and nursery pot style. I've used a lot of different media. All required adjustments in feeding strength.

The suggestion someone made about finding and emulating a grower on the boards whose style and results you like is a good one. It will save you a lot of grief.

The method for determining what strength you should use in your application is quite simple. First, look at your plants. If they are looking good, you've got it! You don't need to go any further. Leave it alone! If they are not, you need to check your ph and ec or ppm with meters. What all those that have gone before you have determined is that pot likes a ph of around 5.8 and a ppm at the .5 conversion (milwaukee meters) of around 950. Be advised that the 5.8 ph recommendation is in the middle of a ph zone that the plants like. Drifting up and down slightly from that number is ok and even desirable.

I am currently growing trees hempy style in 5 gal buckets of perlite. The hempy bucket has a drain hole around 2” from the bottom creating an internal reservoir. Perlite has little cec. When I watered 8/16 strength the overflow after a few weeks would measure 1900 ppm or more with ph way off. The plants were showing symptoms, some yellowing, leaf curling, spotting, and so on. Still growing but it was obvious something was wrong. I began cutting my strength down every watering until the root zone was functioning at 5.7-5.8 ph and 950 ppm. I was still using the lucas ratio but with a much lower strength. I was using, with flora series, 2.66/5.33 ml per gal. A little awkward for measurement, so I rounded it to 3/6. I'm still using the lucas ratio of 1/2, just much weaker to compensate for the nutrients accumulating in the root zone. My mixing container would read 5.1-5.2 ph and 385 or so ppm. Hardly enough concentration and the ph was too low for my liking. But, after a week of watering every other day with this solution I was able to hit my targets in the root zone, which is where it really matters.

dongle69's statement that you can water 8/16 in coco is correct as long as you have a large amount of runoff. Essentially he is using enough liquid to flush the medium sufficiently every time he waters. Genhydro recommends an overflow of 25%. I probably get a 10 or 15% runoff. I don't want more runoff than that because it goes right out onto a concrete floor and I for sure don't want it running out under the door. I resorted to 3/6 strength to hit the target ph and ppm.

The point of all this rambling is to illustrate that every instance of style whether it is active or passive, media or lack of, and lighting will require unique adjustments in strength. The ratio remains the same.
Later, delta9nxs

 

[petemoss]

delta9nxs,
Very well put, my friend! Just a quick question: you wrote "My mixing container would read 5.1-5.2 ph and 385 or so ppm. Hardly enough concentration and the ph was too low for my liking. But, after a week of watering every other day with this solution I was able to hit my targets in the root zone, which is where it really matters." If my starting mix had such a low ph, I would have adjusted the ph up to 5.8. How did you know to leave the ph alone?

 

[delta9nxs]

Hey, pete

I believe it was lucas who wrote that if he were hand watering pots of inert media he would use full strength every third time with water in between or 1/3 strength every time.

I prefer the constant strategy as I feel it gives you more stability in the root zone, I didn't want to adjust anything until I saw which way it was going with each successive watering so I checked ph and concentration immediately after fertigating every other day. By the second watering it was apparent that it was going up. It took 4 waterings to stabilize. I only check it right after watering but it would be interesting to hook up a continuous meter and see what exactly was happening in between. later on

 

[ReeferDan]

Lots of great info and explanations here.

Ive read many lucas threads over the past couple years, but only now am I going to start using it.

I just set up a nice cab with a 400w switchable mh/hps ballast. Temps and humidity and everything are dialed in.

I have a large rubbermaid tub, cut 4 holes with 4" netpots and made a dwc setup. 1 big airpump and 4 small airstones placed underneath each netpot.

My starting water temp is in the mid/low 60* and ph is 6.5-6.7 with 40ppm.

The rubbermaid holds 14 gal of water to the bottom of the netpots, so i went ahead and bubbled it overnight and then added 112ml of Floronova bloom (14gal times 8ml = 112ml of bloom )
I mixed it in and let it sit for an hour or two and checked it again. Water temp was consistent, and ph went down to 5.7-5.8 and ppm was at 900ppm.
Is this about right?
Can i put new clones in this? or should i pour half of it out and add back some more plain water?
Im planning on getting clones tomorrow and putting them in. They are hindu skunk and are supposed to be heavy feeders.

let me know what i should do. this is my first time runing the lucas formula, and ive heard to both use full strength the whole way and to cut it in half, so im interested in what i should do.

Thanks
RD

 

[dongle69]

You have low wattage lighting so that strength may be too much.

 

[ReeferDan]

ok...
one more thing to mention my cab runs VERY cool so i can comfortably leave my hand like 2-3" away from my hood with the metal halide.
I havent played with the hps yet because i need a new bulb but when i had it in there it was 70* like 6" away from the light.
So what im getting at here is even though im not running a 1k watter, i can up the intensity by running the lights REALLY close to the plants

 

[Carboy]

Gotta Ph Question

Gotta Ph Question

I'm sure this has been asked and answered, but there is so much info I haven't found it.

If you add 8-16 / gallon of distilled or RO water, what will the PH read?

If you add 5-10 / gallon of distilled or RO water, what will the PH read?


Thanks -------- Carboy

 

[delta9nxs]

this just in

this just in

hey, carboy!

did this 10 min. ago just for you. i used fresh, newly opened gals of flora micro and flora bloom and new syringes.

ro water 5.9 ph 4 ppm

5-10 5.2 ph 652 ppm

8-16 4.8 ph 975 ppm

 

[delta9nxs]

hydro-soil, first i just wanted to say that you did a great job in your opening post. everything laid out nice and clear. thank you I don't think this is quite on topic, but it's the last, i promise.

i was having so much fun testing ph and ppm (translation: bored) that i decided to do a few more real quick while i had fresh jugs and syringes;

4-8 5.3 ph 488 ppm

3-6 5.4 ph 415 ppm

and finally, and i really mean it

6-9 5.1 ph 708 ppm

to petemoss, please amend my 3-6 readings in my previous post to the above. the first time i was eyeballing hastily poured nutes in a graduated shot glass. this time it is precise as i used unopened nutes and measured with syringes right out of the packaging. all rinsed with ro water between readings.

the 6-9 is not the "lucas ratio" but i thought i would do one as it is what rezdog uses with coco.

 

[Carboy]

hey, carboy!

did this 10 min. ago just for you. i used fresh, newly opened gals of flora micro and flora bloom and new syringes.

ro water 5.9 ph 4 ppm

5-10 5.2 ph 652 ppm

8-16 4.8 ph 975 ppm

Wow!! Custom lab report --- makes me feel all special.

Thanks Delta, i appreciate it.

One more question, if ya don't mind.
Would you adjust any of those PHs when you mix up a new batch or just start the run from there and monitor?

CB

 

[10k]

good stuff delta9nsx, also see this thread for further lucas formula explaination

http://www.icmag.com/ic/showthread.php?t=124122

 

[purpledomgoddes]

there was member here that ran flood and drain tables and flora nova bloom.

did not flush.

anybody running lucas formula, or flora nova w/ other ratios, and not flushing?

 

[lysol]

If this is a stupid question go ahead and laugh but I get the gist this should be common knowledge or something but I have been reading these forums for a while and never really started getting into "dro" until recently.

When you cite an NPK figure such as 60-10-10 or something does that mean 60% of the total _mass_ of the concentrated fertz are pure N elements? Does this mean if you extracted just the solids from the fertz? Can someone elaborate?

When you cite this "lucas ratio" you say 18-6, What is this a ratio of? 18 parts of what to every 6 parts of what? Or does it work more like NPK?

Its not that I dont try and read up, but these typographical conventions are not very intuitive. Can someone pleze coddle me and spell it out? I want to get good at it but I lack the foundations to build upon it would seem.

PS. on a related note anyone know how THC % works? If you say bud has 20% THC and you have 28g of bud does that mean you have .2 X 26g of pure THC?


Another thing, so this thread implies that if I take a bucket and fill it with water with no plant the PH will stabalize? It says if PH goes up I am overferting, but I have no plant ( just kinda practicing while I wait for my seedlings ).... I am assuming if I had a plant the plant actively acts on the PH level?

 

[Hydro-Soil]

Be advised that the 5.8 ph recommendation is in the middle of a ph zone that the plants like. Drifting up and down slightly from that number is ok and even desirable.

I'm getting better results by starting at 5.4pH, since I manually top off twice a day. If you have a float valve doing that automatically for you, start your pH at 5.2.

The pH will slowly creep up as your plants eat the nutes. When you add more nutes it will drop again. It shouldn't be necessary to adjust the pH with pH-Down a whole lot, only a few times throughout the grow.

 

[Hydro-Soil]

there was member here that ran flood and drain tables and flora nova bloom.

did not flush.

anybody running lucas formula, or flora nova w/ other ratios, and not flushing?

If you don't flush, I can taste it. Tastes better than a lot of dispensary smoke and doesn't bother me.

MUCH better flavor with a 1.5-2 week flush.

 

[SafeSwoops]

Thanks so much for taking the time to make it easy to access and understand this info HS... it really helps! My next run is FNB... i'm excited about a one bottle run!

 

[Hydro-Soil]

Thanks so much for taking the time to make it easy to access and understand this info HS... it really helps! My next run is FNB... i'm excited about a one bottle run!

May your harvest be bountiful. Glad I could help.
Just remember that you'll do better running a bit less nutes than optimal vs. a bit more. Don't make the same mistakes I have. They shouldn't be a dark green, just lush and very green, you'll see the difference.

 

[Ioni Botani]

Holy fuck....I dunno why I was missing the whole pH thing...DUH! RO water has no buffer, it takes on the pH (proportionately) of whatever goes in
Thanks fellas!
Simplify!

 

[furley]

Hydro-Soil, could you help with an issue? I pretty much have most of what you say bookmarked and would love a personal opinion.

I started some clones on FNG, and then switched to FNB around 3 days afterwards. I started with full strength FNB as I heard that plants would get deficiencies any lower...

Well half the clones already had some deficiencies from a pH problem before I had a pen (About 5 days in), and then all plants showed signs of nute burn (this was at 900ppm .5conversion)... So I diluted my res to 400ppm... There doesn't seem to be anymore burning (its been 2 days), but half the weak clones (the blueberries) are still getting worse, they appear to have all sorts of deficiencies! (And are additionally now clawing... it only appears the bottom leaves are getting worse)

My question is, are my plants dying because I'm not using 8ml/g? I added 20 drops of superthrive to my res earlier too, I've heard it can help stressed plants a ton.