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Seachem method of potassium dosing

No, not really.

In the end, it's up to you. A good starting point is nitrogen. How much nitrogen do you need? It depends primarily on CO2 & light. If you run high-tech, you'll probably need 10 mg/L NO3-, or maybe even more. In low-tech, see my chart above.
Nitrogen to phosphorus ratio is known, it should be around 16 : 1 [on molar basis]. Similarly, potassium to nitrogen is also a given: 1 : 4 [molar]. There may be more potassium, but not less.
As for K, Mg and Ca, there should be several times more Ca & Mg than K. Mg to Ca ratio is less important than people often believe. Only in hard waters, sometimes there's too much calcium and too little magnesium. If that is the case, you should add magnesium. A ratio 1 : 2 [again, molar] for Mg : Ca is ideal, 1 : 5 still acceptable for most plants.
But what about: "Calcium is an antagonist of many heavy metals, as well as phosphorus." So, there is a precipitation of phosphate in water with high calcium and it needs to be added more to maintain the correct N: P ratio?
I understand and take into account the ratio of Nitrogen and Potassium, but what are the ratios of elements with Calcium? So far, it turns out that there is nothing terrible in the fact that there is a lot of it, but in practice I see that plants do not feel well in water with a lot of Calcium…
On the other hand, I have a lot of carbonates, perhaps they are the reason for the poor growth of plants..
 
there is a precipitation of phosphate in water
Correct. Phosphates are prone to loss in precipitates. The main enemy is not calcium, though, but iron.
You can see that even in my soft water, I dose a bit more (15 %) phosphorus relative to nitrogen.
I see that plants do not feel well in water with a lot of Calcium
Some plants simply hate hard water, that's a hard fact. Yet there are still many which tolerate it, possibly some even prefer.
I have a lot of carbonates, perhaps they are the reason for the poor growth of plants
Correct. If you're using RO water and your rocks dissolve that quickly then you'll probably have to get rid of those rocks.
There's one more danger in that: It scavenges CO2. The reaction goes like this: CaCO3 (s) + CO2 + H2O -> Ca(HCO3)2.
Still, many aquarists use calcite rocks for decoration and the dissolution problems are manageable. What about your substrate? Is it rich in calcite?
 
Correct. Phosphates are prone to loss in precipitates. The main enemy is not calcium, though, but iron.
You can see that even in my soft water, I dose a bit more (15 %) phosphorus relative to nitrogen.

Some plants simply hate hard water, that's a hard fact. Yet there are still many which tolerate it, possibly some even prefer.

Correct. If you're using RO water and your rocks dissolve that quickly then you'll probably have to get rid of those rocks.
There's one more danger in that: It scavenges CO2. The reaction goes like this: CaCO3 (s) + CO2 + H2O -> Ca(HCO3)2.
Still, many aquarists use calcite rocks for decoration and the dissolution problems are manageable. What about your substrate? Is it rich in calcite?
What about iron?
How much NO3: PO4 do you keep?
How does the phosphate precipitation reaction occur? Let's say there are 0.1 phosphates in water, after adding calcium, it decreases and becomes inaccessible to plants? Or does it happen in some other way?
 
Hi all,
Erm, yes but your starting point is rain water, so you have a big advantage, ie soft water
Point taken, it definitely makes keeping ions in solution easier.

I don't use rain water <"If it's yellow, let it mellow and RO is the devil"> specifically because of its softness, I use it because I've always used it, from long ago, back before <"I was a planted tank keeper">.
As Vin points out, the top right corner is blank.
I think I know the reason, from my experience of waste water work, you would grow a lot of green filamentous algae.
But what about: "Calcium is an antagonist of many heavy metals, as well as phosphorus." So, there is a precipitation of phosphate in water with high calcium and it needs to be added more to maintain the correct N: P ratio?
If you get a lot of calcium (Ca) ions in solution they will interfere with the uptake of less abundant cations, it is just a numbers game. <"Nutrient antogonism"> .
Phosphates are prone to loss in precipitates. The main enemy is not calcium, though, but iron.
Yes, ferric iron (Fe III) is the preferred precipitant for phosphate (PO4---) <"Iron phosphate">, but most phosphate compounds are insoluble. If you ignore sodium (Na) salts it is only really potassium and dipotassium phosphate (KH2PO4 & K2HPO4) that are soluble <"Potassium Carbonate (K2CO3) vs pH ?">.

large_solubility_rules_chart-mk-png-png-png-png.png


cheers Darrel
 
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