Precipitation with alkalinity additive

[mginn]

I have a 55 gallon tank with mostly LPS and some softies and clam. Recently addded slow kalk drip at night for top off around 1/2 gallon. To maintain alk/calcium levels my two part dosage has significiantly increased. I have needed to add 400 ml of each additive daily to try and maintain levels. After dosing getting a CA 400 and alkalinity 10 but by morning alkalinity is at 7 only 12 hours later. I noticed precipitation when adding alkalinty this AM so there is some sort of super saturation. Unsure what is going on since CA/Alk seem to be in proper ratios. Mag 1400. That is a massive amount of additive for 55 gallons. All corals/fish look happy and healthy. Any suggestions for solving this ? Thanks

[bertoni]

Do you see precipitation or just temporary clouding? Whenever kalk is dripped, you're likely to see some cloudiness in the immediate area of the drops, because magnesium hydroxide will precipitate temporarily:

http://reefkeeping.com/issues/2005-07/rhf/index.php#6

Here's an image:

http://reefkeeping.com/issues/2005-07/rhf/testpop.htm?images/Figure_3.jpg

I agree that 400 ml seems like too much. How are you dosing the two part? Is that on a drip as well?

If it's not too difficult, I think getting second opinions on the test kits might be useful.

[MCsaxmaster]

I've experienced cases where the kalk was pushing the pH high enough that I was getting very high rates of abiotic precipitation on pumps, heaters, albeit unnoticed at first and saw the issues you're seeing. I'd try haulting the kalk for a few days and see if you can get the alk and calcium stablish with just the two part, then perhaps start dripping undersaturated solutions of kalk (e.g., 1/4 tsp per gallon at first, instead of 2 tsp per gallon) and slowly increase kalk concentration to see what you get.