[untamed]

Originally Posted by ed99

I'm having the same problem, and I am also using Ocean Pure Pro salt. I wonder if this is part of the cause. I'm trying to maintain an alkalinity (KH) of between 7 and 8, and do this I have to add 3 heaping teaspoons of Seachem Reef Builder alkalinity booster every 2 days in a 200 gal aquarium. One thing I have noticed is that I lose about 0.5 of KH every day, so it is not an instantaneous reaction. Could it be that some carbonate minerals are precipitating out in that time frame?

My calcium levels have stayed high (425-450ppm) and magnesium levels are also high (1450-1500 ppm) at a salinity (SG) of 1.024. I tested a new batch of the salt and it gave me a [Ca2+] of 525 ppm and Kh of 9.5 at a salinity of 1.0255. By the way I am using Elos test kits.

Ed

I assume that you are using some sort of balanced Ca/Alk supplement. Generally speaking...if you are measuring low Alk it probably means that you aren't adding enough of the balanced supplement. You might think that more balanced additive would drive BOTH Ca and Alk up...but it doesn't work quite like that.

Another way of saying the same thing...is if you are not adding enough balanced additive (ie: Ca Reacter running to low, or not enough Kalk, or not enough C-Balance etc....), you'll see low Alk before you see low Ca.