How to minimize calcium content in a reef tank?

Answer 1

Typically you wouldn't want to lower the calcium level in a reef tank. Basically, any reef-building animals (hard corals) will pull it out of the water as they use it to build their skeleton.

Also, because calcium bonds with carbonate and other salts, it is part of a buffer system for the tank, and is depleted as it reacts with acids in the tank (produced by metabolic activities of all living creatures).

Technically, you could have so much calcium in the tank it precipitates out, but would likely not cause any trouble with the inhabitants. If there are no corals taking calcium out of the water, and nothing reacted with it (like the acids from fish waste), then it will eventually precipitate out of the water. Basically, you would need to stop adding calcium to lower it in the tank -- but it just seems like the last thing you'd want to worry about.

If you are really concerned, send an email or pm to me and I'll get a better answer for you.

Hope it helps!

Answer 2

Why do you want to minimize it? Every partial water change you do will add more, and your corals will make use of it too. There are calcium test kits as well, that's probably the best way to keep an eye on things.