Calcium dropping

WhiskeyCoffee · Nov 14, 2017

Hello all,

I have a newish (3 months) 75g tank that I started with dry rock, and so far I only have 2x Montipora Digitata, finger leather, zoas, and candy cane coral. No coraline that I can see anywhere. Before adding the corals my calcium was steady around 500ish and now in the last week it dropped to 480 and now 450.

My question is, would that small amount of corals cause the calcium to drop that much? I'm pretty sure the digitatas are growing as the white tips look "bigger" if that makes sense.

Thanks!

Flippers4pups · Nov 14, 2017

It's possible, especially if your rocks and tank walls are encrusting in coraline algae.

NorthFLreefer · Nov 14, 2017

Yep! Corals consume calcium! Look into dripping Kalkwasser, or dosing calcium, alkalinity, and Mag, depending on tour tanks demands

Randy Holmes-Farley · Nov 15, 2017

If the alkalinity also dropped (by about 7.4 dKH) or if you may have added enough buffer or alkalinity additive to supplement against that alk consumption, then the calcium drop is real.

If alkalinity did not drop substantially, then the calcium drop is likely testing error. Except by water change with a low calcium mix, calcium cannot drop a lot without alkalinity being consumed.

WhiskeyCoffee · Nov 15, 2017

Randy Holmes-Farley said:
If the alkalinity also dropped (by about 7.4 dKH) or if you may have added enough buffer or alkalinity additive to supplement against that alk consumption, then the calcium drop is real.

If alkalinity did not drop substantially, then the calcium drop is likely testing error. Except by water change with a low calcium mix, calcium cannot drop a lot without alkalinity being consumed.

I had a feeling some advanced chemistry might be going on here.

So actually my pH was around 7.8/7.9 and I raised it to 8.0 by using outside air with my skimmer. Additionally my KH was around 8 and I raised it to 10 (slowly) using baked baking soda. Any thoughts?

Randy Holmes-Farley · Nov 15, 2017

WhiskeyCoffee said:
I had a feeling some advanced chemistry might be going on here. So actually my pH was around 7.8/7.9 and I raised it to 8.0 by using outside air with my skimmer. Additionally my KH was around 8 and I raised it to 10 (slowly) using baked baking soda. Any thoughts?

Sounds like a fine plan, and now you should look to dosing calcium and alkalinity in a balanced fashion, such as with a two part system.