Dosing Ca increases, alk dosing goes down

[jaysonsd]

Hey everyone,

My tank is 'healthy' in my opinion with sps growing (I do like that growth tips are a different color to keep me in the know that its all good). One thing I've noticed from my compulsatory test kit measuring is that my Calcium dosing has to keep getting increased every 5 days or so while I have to dial back my alkalinity dosing.

It is sps dominate, but no new major additions. I did increase my alkalinity up to ~10-10.5 three weeks ago when it used to hover around 8-9. Still wrestling to get my nitrates below 5, but Mg has been kept above 1200 regularly. I would think if everything is doing good, both values should be sucked down at a near equivalent pace.

When the tank was far from stable and I was neglecting, the rare times I tested, I noticed my alkalinity required ever increasing corrections and calcium never needed adding.

Any suggestions? I'm unsure if ambient CO2 levels inside are high (its 'cold' down here this time of year) and affecting pH (which swings way more than 0.5 in a 24 hour cycle) and affecting alkalinity in some way that escapes me. I'll do the outdoor test this weekend.

Thanks much,
Jayson

[Randy Holmes-Farley]

What are you dosing?

What salt mix for water changes and what is the current calcium level?

[jaysonsd]

Scripps NSW which runs low on Mg and Ca (1150 and 370 from last tests), two part and Mg are dosed through pumps hooked up to my acjr. But now I just realized my Mg - 1200- is low for suggested levels (which is supposed to stabilize my alk/ca).

[bertoni]

1200 ppm is fine for magnesium. The canonical average seawater value is 1285 or so. I suspect that the water changes are changing the parameters.

[jaysonsd]

But then wouldn't both be going down with the water changes? And I do treat the wc prior addition.

[bertoni]

That depends on the dosing rate, which is hard to judge.