Some Nutrient Questions

B.B. King · Mar 2, 2013

I've been running raw salts for a couple of years now, and am beginning to have enough knowledge to know some things I don't Know.

1. Water Analysis. I figure my W.A. into my formulation, but are all those elements in a form which is available to the plants?

2. is CaCO3 plant-available? Does it dissolve into such a form in solution? I see GH uses it in a couple of cal-mag products.

3. does acidifying the solution free up unavailable ions? Seems like I read that somewhere.

4. if the solution pH goes too high, and precipitation occurs, can it be reversed by dropping the pH?

5. finally, the $20,000 question: What are the differences in formulation between pure hydro, and soil (or similar cec-containing media)? I'm growing in bio-buckets (RDWC) which has pretty much zero cec. It seems that the wisdom a couple of years ago was a K:Ca:Mg of 3:2:1. Now I'm seeing higher Ca, and lower K. Could be other issues, but it seems I did better the old way. Is that maybe the difference between hydro and coco?

Many thanks for any thoughts you may have!

Grow well,
B.B.

squiggly · Mar 2, 2013

B.B. King said:
1. Water Analysis. I figure my W.A. into my formulation, but are all those elements in a form which is available to the plants?

Not enough info

2. is CaCO3 plant-available? Does it dissolve into such a form in solution? I see GH uses it in a couple of cal-mag products.

Under acidic conditions it will dissolve following an equilibrium constant in accordance with the acidity of the solvent--this is what is currently happening to our coral reefs and many crustaceans worldwide.

3. does acidifying the solution free up unavailable ions? Seems like I read that somewhere.

This works in both directions for different ions (acidifying/basifying)

4. if the solution pH goes too high, and precipitation occurs, can it be reversed by dropping the pH?

In most cases, yes. Sometimes heat may need to be applied.

5. finally, the $20,000 question: What are the differences in formulation between pure hydro, and soil (or similar cec-containing media)? I'm growing in bio-buckets (RDWC) which has pretty much zero cec. It seems that the wisdom a couple of years ago was a K:Ca:Mg of 3:2:1. Now I'm seeing higher Ca, and lower K. Could be other issues, but it seems I did better the old way. Is that maybe the difference between hydro and coco?

Can't help you here too much. If Ca has been coming up they've probably found better ways to keep it in solution. Ca loves to precipitate, most Ca salts are highly insoluble unless conditions are very acidic or the Ca ion is thoroughly chelated.

B.B. King · Mar 2, 2013

Many thanks for the concise reply!

re #1:

I'm thinking this still isn't probably enough info, since it doesn't state what form any of the elements are in? Anyway, it's all the info I have on my water.

re #5:
I guess I'm asking what, in general, would be the fundamental differences between nutrient formulations for pure hydro vs. dirt.

Grow well,
B.B.

squiggly · Mar 2, 2013

B.B. King said:
Many thanks for the concise reply!

re #1:
View attachment 293846
I'm thinking this still isn't probably enough info, since it doesn't state what form any of the elements are in? Anyway, it's all the info I have on my water.

They should be available at their various optimal pH values--the test names these "soluble salts" which is the key. In order to be soluble these species must be ionized.

re #5:
I guess I'm asking what, in general, would be the fundamental differences between nutrient formulations for pure hydro vs. dirt.

Not super knowledgeable here but my first guess would be chelation. Hydro will need to be more heavily chelated to prevent precipitation as solution concentrations are altered through the uptake process.

montanamike1 · Mar 2, 2013

B.B. King said:
Many thanks for the concise reply!

re #1:
View attachment 293846
I'm thinking this still isn't probably enough info, since it doesn't state what form any of the elements are in? Anyway, it's all the info I have on my water.

re #5:
I guess I'm asking what, in general, would be the fundamental differences between nutrient formulations for pure hydro vs. dirt.

Grow well,
B.B.

I agree with squiggly 100%, in Hydro it's all about cleanliness; you want to have the minimum percentage of solid matter (insoluable nutrient combinations/concentrations) in your system and the maximum percentage of readily available nutrients. For this reason many recommend fully synthetic lines like Dutchmaster or Gen Hydro for RDWC systems.

B.B. King · Mar 3, 2013

I mix my own formulations from raw salts (synthetic). I was asking more about nutrient ratios for hydro vs. dirt.

I've been scouring bottled nute labels, and I think a bit more light is creeping in. GH Maxigrow powder contains Calcium Sulphate. Flora Micro and several GH Cal-Mag products contain Calcium Carbonate. I also saw Calcium Chloride and Calcium chelate on other labels. Presumably, there are calcium options beyond Yara.

Back to question #5, here's an example from the bottled nute world. Botanicare CNS17 Grow:

Hydro Coco

N 91 91

P 26 13

K 101 50

Mg 15 15

Ca 85 109

Not that this is the Holy Grail or anything, but it seems that most manufacturers who put out both hydro and coco/dirt formulas follow the same trend. Hydro gets more P & K, and less Ca. Enlightening, to say the least.

Grow well,

B.B.