Lucas Formula Issues...

[rollinthc]

I am trying to use the lucas formula, anyone familiar with it? I'm having troubl with the phosphorus count in the formual, it seems there is an error or something I'm doing wrong...

the ppms of florabloom which is 0-5-4 at 16ml/gallon concentration seems to me to be 210ppm of phosphorus..and not the 105ppm as stated for balanced flower cycle as stated in many threads of:

N:100
P:100
K:200

if the floramicro at 5-0-1 and 8ml/gallon is 105ppm of nitrogen, then if you double the concentration of the bloom (16ml/gal), the ppms will double on the phosphorus side...

I got the 210 (or so) from a basic conc. formula:

[(ml solute) x (% solvent) / ml of solvent] * density weight of nute

so [(16ml x 5%) / 3.7 liter] * 1.00

(the 1.00 should really be 1.15 density from GH florabloom:
Net Weight (grams): 4360.00
Liquid Vol (ml): 3790.00
4360/3790=1.15, however just using 1.00 for the above)

The above gives a ppm of 211.34 ppm


Any help here would be appreciated!

 

[captain.koons]

Bloom @ 16ml = 106 PPM P

It's not 5% elemental P but 5% P2O5 aka phosphate pentoxide. I'm not sure how you got your 210 ppm value?

Use a nutrient calculator and it will simplify things.

 

[Str8Dank]

look here fatman gives a great breakdown about nutes but specifically touches on lucas in his post.



i run lucas with some additives. i wont lie i dont pay as much attention to the npk and ppm of each element as i should. i just give the plant what i think it needs and use the lucas as a base. now I'm running it with H&G additives because i had those from a past run and had micro and bloom from a past run so I'm using everything up. so far so good.

 

[rollinthc]

I got the 210 (or so) from a basic conc. formula:

[(ml solute) x (% solvent) / ml of solvent] * density weight of nute

so [(16ml x 5%) / 3.7 liter] * 1.00

(the 1.00 should really be 1.15 density from GH florabloom:
Net Weight (grams): 4360.00
Liquid Vol (ml): 3790.00
4360/3790=1.15, however just using 1.00 for the above)

The above gives a ppm of 211.34 ppm

 

[rollinthc]

I think I found my own answer: the 210 ppm is CORRECT per the listed labeling on GH productline and most fertilizer manufacturers (some are listing it truly what the concentration is)...

P2O2 is 44% elemental only
K20 is 83% elemental only

so that the 44% applied to the ppms gets you to 106ppm of P (after weight density is calced in).

So the GH label SHOULD say, technically, N-P-K, 0-2.2-3.3,
MOST manufacturers do not put this on the label for fear that the consumer would be feeling cheated out of product, and technically, it is only 0-2.2-3.3 of N-P-K

Cool! :happy thought I was going crazy

 

[Bobby Smith]

I basically just trust that Lucas knew what he was doing and use that as my base flowering formula (with a couple of additives) - pretty sure if his math was off that we'd have heard about it by now.

Just my thoughts.

 

[kuz]

So the GH label SHOULD say, technically, N-P-K, 0-2.2-3.3,

Right, but any guaranteed analysis will list P2o5 and K2o. It must have been some kind of genius marketing ploy to keep customers confused. There was probably some reason for doing it that way, cant change now or you really confuse everybody.

 

[captain.koons]

They do say that it's 5% P205 and not 5% P.

The 0-5-4 or whatever it is is misleading but on the back the labels say 5% Phosphorus from P205 , whatever soluble potash from K2O, etc.

 

[rollinthc]

Thanks for all of the replies on my 1st thread!

On another point: Now I am looking at the trace micronutes thats needed for the grow... GH line does not have some of the micronutes, even if all three parts are used, whats up with that, do I need to supplement with some other micronutes?>

 

[captain.koons]

What's missing? I think Micro contains it all.

 

[rollinthc]

From my spreadsheet for GH floras: G, M, B

The total nutrients on a (0-8-16) are:

Nitrogen (N) 116.68
Phosporus (P) 96.28
Potassium (K) 164.66
Magnesium (Mg) 65.64
Sulphur (S) 43.76
Calcium (Ca) 116.68
Iron (Fe) 2.33
Boron (B) 0.00
Manganese (Mn) 1.17
Zinc (ZN) 0.00
Molybdenum (Mo) 0.19
Sodium (Na) 0.00
Copper (Cu) 0.00
Chlorine (Cl) 0.00
Cobalt (Co) 0.12
Silicon (Si) 0.00
Selenium (Se) 0.00

I think the iron and Mo and Mn are good (?) but it is missing Cu, B, Z and Fe...

What do all of ya think?

Here is the only thing I found on the requirements for Mj plant needs..

"The trace minerals a plant needs are boron, copper, molybdenum, zinc, iron and manganese. The marijuana plant takes up a minimal amount of these elements, but they are essential to the overall well-being of the plant."
Source:

 

[tortuga1503]

man i had issues with the Lucas Formula and OG`s but everything else was rocking. I love the simplicity of the Lucas Method. I want to go back to it the next run. BS what additives do you use with the LF? If you dont mind me asking. Do you add back 1/3 of nutes to maintain the same ppm or do you add back plain water till you have replaced total rez volume? I really need help with this formula because I am spending way to much with what I am using now