Water Changes

[bosko]

I'M WONDERING HOW MUCH IF ANY CALCIUM THE TANK LOOSES WITH A WATER CHANGE. I'M DOSING CALCIUM FOR CORALS AND CLAMS

[Jason Donohoe]

It depends on the ASW you are replacing it with. A lot of salt mixes are calcium deficient and as a result will lower your calcium concentration with water changes.

[kraze3]

It depends on what your water change water is and your tank water. Also depends on the amount of water your changing. If your new watwer and tank water are close then your not losing much. If your tank is much higher and yur doing a large water change you could be losing a fair amount.
You can test your water in your DT then your water change water. Do your water change then retest the tank, or you could figure it mathematically

Here is a salt thread
http://www.reefcentral.com/forums/sh...readid=1287118

[seapug]

If you use a salt mix and source water with a consistent makeup over a period of time and don't use massive amounts of calcium/alkalinity supplements in the tank, it is quite difficult to "lose" calcium with a water change.

Even if you have no stony corals minute amounts of calcium are precipitated from the water by the biological process that take place in a marine tank, so you can probably be quite certain that the water you remove with a water change has a lower calcium level than the new water you put in.

If you really want to know exactly how it affects your calcium, get a test kit and measure the level before and after a water change and see how they compare.