kekon

I noticed strange thing. I wanted to make solution PO4 + NO3 composed of Ca(NO3)2 and KH2PO4. Having mixed the salts in the distilled water the solution got murky and sediment was produced on the bottom of the bottle. The sediment resembles seeds of CaCO3. I don't know what it is; probably a chemical reaction occurs. I tried the same mixing KNO3 + KH2PO4 and the soultion was very clear, without any sediment. I'm not any good at chemistry but it worries me that the same chemical reaction occurs in my tank and the sediment produced is just important micronutrient rejected in the reaction. The sediment is not soulable in the water.
Is it Ca ?

banderbe

Drop some muriatic acid on it.. if it's calcium you'll know because of the fizzing.

kekon

I've just added a few drops of HCl into the solution and the sediment has dissapeared immediately, but there wasn't fizzing. I asked the question to chemists but they haven't answered yet.

Cichlid Freq

The HCL may have dropped the pH of your solution enough to dissolve the calcium the precipitated out of solution.

fabry

Kekon,
if you mix together Calcium Nitrate and Potassium phosphate the two salts dissolve easily at first because they have a good solubility.
So you obtain a solution having Calcium, Potassium, Nitrate and Phosphate ions going around and mixing togheter.

When Phosphate ions meet Calcium ions they react and combine together forming Calcium Phosphate (Apatite) that is highly insoluble, thus precipitating very quickly and leaving in the water only Potassium Nitrate.

Adding Hydrochloric acid you cannot have fizzing because there are no carbonates being turned into CO2 (but just Apatite) so all you can obtain is dissolving a few of Apatite obtaining Calcium Chloride.

Regards.

Fabrizio.

kekon

The chemists told me calcium phosphate is produced. Hopefully both PO4 and NO3 are detectable in the tank.
I measured pH of the solution after adding some HCl. It is about 3.4. I think adding 2.5ml of the solution daily will not affect pH in my tank (200 liters)