Using 2 part Ca/ALK additive and getting low Calcium levels…

[rocknut]

I have been using a 2-part calcium/alkalinity additive on my 20 gallon SPS tank since I set it up a few months ago. In order to keep my alkalinity level where I want it (around 9 dKh) I have to add 6.5 ML of the ALK portion of the additive. If I add the same amount of the Calcium part, my Calcium levels end up dropping below 400 ppm. So, I have been adding 9 ML of the Calcium additive. I know that one of the big advantages of using the two part additives is that they keep everything Ionically balanced, and that by adding different amounts of the two parts I am loosing this benefit.
Anyway, by doing this I end up with a half full bottle of the ALK component by the time I finish the Calcium bottle, and since as far as I know, you can only buy the two part solutions in two parts, I keep wasting this half bottle.
Would I be better off using the two part solution in equal parts, and then just adding a separate calcium additive to make up the difference? Someone also recommended using only a calcium additive like Tropic Marin Bio-Calcium which adds ALK buffer along with the Calcium. I’m assuming this just raises both levels equally? Would I just adjust the dosage to get my ALK level in line, and then hope that the calcium level falls into place?
Thanks in advance for the help!
Rocky

[Boomer]

You do not need to add the Ca++ part, just the Ak part. One of the methods for lowering the Ca++ is to raise the Alk, especially if you high Ca++. The Ca++ attaches to the Alk component CO3--, = CaCO3, a precip and your Ca++ drops.

What is Your Ca++ ?

You should just add the Alk part of the two part, that is it. Many do this and it is fine :)

[rocknut]

I try to maintain my calcium level anywhere in the range 420-450 ppm. Currently I have it fairly steady at 420 ppm, but like I said, to do this I have to add around 50% more of the calcium component than the ALK component (6.5 ML of the ALK, 9 ML of the Calcium). If I add them in equal parts my calcium will drop below 400 ppm.
I think I may have been unclear in my original post. I have no problem keeping my ALK level steady, it is the Calcium I am having trouble with (keeping the levels elevated and above 420 ppm). I definitely don’t need to lower my Calcium levels.
Thanks again

[Boomer]

You should have no problem keeping the Calcium at 420 and the Alk at 9 dKH. There is something else going on. Noramlly Alk drops much faster than calcium and your is the opposite. There is no need to keep the calcium any higher than 420. You could boost it up with kalk. Many use both kalk and two-parts when one does not meet demands. But your current water chemisty is causing the calcium to drop, not animals

Who's test kits are you using ? Have you added or what else do you add to the tank ? Usually, when we see issues like this, the tank is out of balance, due to something added. And it's time for a water change.


edit;

I just noticed you have a calcium reactor, is this running, you do not say ?

[rocknut]

I need to change my profile, that was my previous tank. I am not currently running my calcium reactor.:) I am using Salifert test kits for both ALK and Calcium. As far as other additives, I am using Tropic Marin Pro Coral Trace elements (and I have only been adding those for about a week.) I use a half cup of Two Little Fishes Hydro-carbon, and I use a Phosban Reactor with Phosban media. I do a 15-20% water change using Tropic Marin Pro Coral salt every week. Here are the other levels:

Salinity - 1.025 (refractometer)
ALK - 9.6 dKH (Salifert)
Calcium - 420 ppm (Salifert)
Nitrate – Undetectable (Red Sea)
Phosphate – Undetectable (Salifert)
Magnesium – 1320 ppm (Salifert)

[rocknut]

One more piece of information that might be relevant that I forgot to add. I have had a difficult time keeping my pH up ever since I first set up this tank (about 10 weeks). I never see anything higher than 8.0, but more typically 7.8-7.9 with as low as 7.6 in the middle of the night (I also calibrate the probe on a regular basis). I basically attributed it to lack of fresh air around the tank. I have more than enough circulation (around 750 GPH) in the 20 gallon system, but because I live in Arizona, I don’t have the windows open all that often (especially this time of year.)