Question for SK8R

[tzylak]

What do you mean about "Alk and cal will not rise if mg is low ", mentioned in you tank specs?
Please elaborate.
-I don't check my mg and alk and cal has always been low. Maybe that's the crux of my problem. . .
Thanks.

 

[billdogg]

I forget the exact reason, but yes - if your Mg is low you won't be able to dose enough of either Ca or Alk supplements to get them to come up. I had forgotten about the relationship until nudged on here. I got the Magnesium back up and the problem disappeared.

Repost your question in the Chemistry forum so Randy can give it a shot or do a quick search - I'm sure some of his past writings will come up.

 

[Sk8r]

It's like a three-legged stool, only kind of a magical one in which one leg is the standard. If you have to adjust chemistry, you can pour alk and cal in with no lasting result...unless you raise mg first. Raise that to about 1300 (which gives it some wiggle room) and THEN when you add buffer and calcium, the readings will stay where you put them until the mg runs out. I think the trick is that the alk thing is just buffer, which controls acidity/alkalinity of the seawater, which is how able it is to dissolve calcium, which is the name of the game. When you supplement calcium to the hungry stony coral, it sucks it up fast, but kalk goes on pouring calcium into the tank, and the buffer allows the water to stay at the right ph range; and the mg helps hold the buffer steady...I'm far from sure of that scenario, because I was NOT my chemistry prof's star student, but that's operationally how it works, at least.