Ca parameters

[Ferguson]

In general, what are the parameters for Ca in seawater? I just tested mine and it is at 500 mg/L (or whatever the units are). I use Kalkwasser. Everything I can find says it should be at least 420-440, but no one gives the upper limit. Thanks.

[fishdoc11]

Calcium is super saturated in seawater at 500ppm(not meq/L) given "normal" temp and alk. This basically means it's really hard to get more than that disolved. Over 400ppm is where you "need" it and around 450 is where you "want" it. Although I have seen at least one tank on this website that had great sps growth at 350ppm. Natural seawater runs about 400-420ppm calcium.
Chris

[Ferguson]

I assume this means I should ease off the Kalkwasser for a while?

[aquaman67]

Here's some light reading that may clear things up.

http://www.advancedaquarist.com/issues/nov2002/chem.htm

[fishdoc11]

That's a great article. For that matter that magazine has alot of good info. If you go to archives you can research several common and not so common subjects. I am the wrong person to ask about kalkwasser since I have never used it. Several people in the the club do, rcmike and reewik I know do. I'm sure there are several others.
Chris

[Sir Knight]

I assume this means I should ease off the Kalkwasser for a while
There are a lot of checks and balances when it comes to calcium saturation. pH, Alk, Meg, etc. Test these also just to make sure your system is balanced. 500ppm is very hard to maintain without effecting the others, both positive and negative. Also coral load. Your system may not be using what you are adding. It maybe too much of a good thing. I have used kalkwasser for many years. What you need to do is find a set point for your tank (this changes every time you add another coral, take one away, etc. Then add the solution as needed. It you have an SPS setup you would need more lime water then a system that is soft, remember there are other things living and growing in your system that uses calcium like Carolline algae. Just so you don't think just because you don't have any hard corals in your tank you don't need lime water, you do, but maybe not as much.
Here is a way to start. Today or tomorrow stop adding kalkwasser to your tank. check your calcium, alk, pH every day until you get down to lets say 425, which is a good level, now dose. check you levels again if you are up to 450 or still at 425.
check the next day again. the goal is to know much you will need to add to maintain 425 - 450 daily. it sounds like a lot of work but it really isn't it should take a week or two to find your check point.

Again every time you add or remove corals,etc the set point may change.

Hope this helps

[Ferguson]

Thanks to everyone for all the suggestions and help. John.

[EvilMel]

Whenever I try to really raise my Ca into that 450 ppm range my alkalinity takes a nose dive.

I had sps growth (not alot of sps in my tank previously) with under 400ppm, but now that I have more sps and a clam I am trying to maintain it at a higher lever (around 425).

I guess I have the opposite (and more difficult) problem.

I'm just going to start adding limewater to get it up to where it needs to be then maybe my Ca reactor will maintain it there.

[fishdoc11]

Have you tested your Magnesium Mel?

[A. Critter Killer]

I don't have any literature to back mine up, but I have had limited success with calcium levels ranging from 350p.p.m.-700p.p.m. sps seem to do poorly, for me, below 380p.p.m., and above 620 p.p.m. Softies and lps don't seem to mind so much. Personally, I have had the best results around 475-525. Just my two cents. ----Sean