# Chemistry: Adding CaCl2



## Reckon (Jul 25, 2012)

Some plants had deformed new growth and I wasn't sure if it was overdose of K or a lack of Ca (a bit lean on equilibrium the last week), so I tried adding CaCl2 to my macro solution that already has K2S04, KNO3, KH2PO4, and MgSO4·7H2O; however, I ended up getting a lot of white chunks (like cottage cheese) in my solution. Have I made a mistake in adding Ca to the current solution? 


Thanks!


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## Reckon (Jul 25, 2012)

Ok, so after a bit of research I found this: CaCl2 Macro Mix Problem - Aquarium Plants

CaCl2 + 2 KH2PO4 = Ca(H2PO4)2 + 2 KCl

KCl is soluble. I must be seeing Ca(H2PO4)2 .

My next question is, can I still add this to the water column?


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## Transposon (Sep 19, 2012)

I though Ca(H2PO4)2 is soluble?

From: http://wserver.scc.losrios.edu/~nussl/chem401/handouts/week09/SOLUBILITY RULES.pdf

Could the precipitate be CaSO4·~0.5H2O (plaster of Paris) or CaSO4·2H2O (gypsum)?

Substance..............Solubility................

Ca(NO3)2...................121.2.....(dissolves readily)
CaCl2	........................74.5......(dissolves readily)
Ca(H2PO4)2................1.8........(somewhat difficult to dissolve)
CaSO4.2H2O...............0.255.....(somewhat difficult to dissolve)
Ca3(PO4)2..................0.002.....(very hard to dissolve)

Units of solubility are given in grams per 100 grams of water (g/100g) 20°C 1 atmosphere pressure.

From: http://en.wikipedia.org/wiki/Solubility_table

Anyways, if you keep adding CaCl2, maybe the Ca2+ will keep precipitating out either the phosphate or sulfate ions... until equilibrium is reached?


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## Reckon (Jul 25, 2012)

Hm. Maybe in a more dilute solution. Thanks, I'll try dosing it tomorrow morning.


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