Liquid fertilizer PPM doubts

vcasqui said:

I know that ShroomDr mentions in his thread that some products do not register EC, or they register too much EC in comparison with the actual "food for the plant" in them;

Click to expand...

vcasqui said:

Hello guys, I need your wisdom:

I readed ShroomDr's Nutrient Formula... a while ago. I liked the idea of mixing my fertilizers to give the right amount of nutrients to my plants, so I measured the weight of them and did the following calculations (I want to know the amount of nutes in 1ml/L):

Veg fertilizer (10-7-9): 1'2gr/ml -> ((1'2*1)/1000)*1000000 = 1200 ppm
N - 1200 * 0'1 = 120 ppm
P - 1200 * 0'07 * 0'436 = 36'6 ppm
K - 1200 * 0'09 * 0'83 = 89'6 ppm
Total = 246'2 ppm

CalMax (2-0-0)(3 Ca - 1 Mg) -> 1'1gr/ml -> 1100ppm
N - 1100 * 0'02 = 22 ppm
Ca - 1100 * 0'03 = 33 ppm
Mg - 1100 * 0'01 = 11 ppm
Total = 66 ppm

The thing is, when I measure the ppm with an EC meter, I get:

Veg fert: 1ml/L = ~0'3 EC (150 ppm)
CalMax: 1ml/L = ~0'35 EC (175 ppm)

I know that ShroomDr mentions in his thread that some products do not register EC, or they register too much EC in comparison with the actual "food for the plant" in them; but the readings I took are way too far off when compared to the calculations I did.

So my questions are: Are my calculations correctly done? Should I feed my plants following these calcs?

I usually trust maths above anything else, but I also don't want to kill my plants. If I want to achieve, say, 200ppm of Ca, then I should give them 6ml/L of CalMax (~2'1 EC), which looks crazy to me (and it's waaaay above of the 1'5ml/l recommended by Grotek).

So that's why I need your help. What should I do? I need you.

Thanks

Click to expand...