Ca stuck below 400.

[DNA]

My parameters are stable within the recommended ranges, but Calcium has stayed at around 380 for many years. I have magnesium and calcium sources in my calcium reactor so the supply is stable using a dosing pump and when I fire up my kalk reactor as well Ca nudges closer to 400, but I rarely see higher numbers. At the same time the calcium load from corals can be from very low to moderate and the pumps wear down from abrasive effect of the excess Calcium in the water.

I've got Red Sea and Salifert Ca test kits. The Salifert will show lower numbers as it ages, but the Red sea kit also shows low values.
I keep Ph at 8.4 and Alk at 9, but it is used up faster than Calcium, even with hardly any corals present in my 400g system.

380 should be fine, but my tank has for years killed all SPS test frags in two weeks so figuring this out is a part of the problem solving.
I guess my main question is if Ca can be fully saturated in my tank below 400?

 

[Randy Holmes-Farley]

I guess my main question is if Ca can be fully saturated in my tank below 400?

Saturated is not the right word (it is actually above saturation of calcium carbonate in all reef tanks above pH 7.7), but it may be adequate/plenty for organisms at 380 ppm.

That said, it is easy to boost the calcium wherever you want with calcium chloride. I'd aim for 420 ppm. IMO, 400-550 ppm is fine.

 

[DNA]

Thanks for your reply.


My Calcium reactor is rated for my 320g tank, but is not able, at pH 6,2 and flow at 50ml, to raise Calcium levels above 380 in it, even without any corals. A friend has a comparable setup, but with fully loaded tank and higher Ca levels.

I have kalkwasser and a Bucket of Calcium Chloride, but my pumps will seize up and wear down fast if I use them. My next questions based on your last answer is if there can be a chemical reason for test kits to constantly show lower values than they really are?

 

[Randy Holmes-Farley]

Just make a manual one time correction with the calcium chloride. It would be a bad plan to try to use the reactor to dissolve more CaCO3 because each 20 ppm rise in calcium would cause a 2.8 dKH rise in alk.