Alk drop

[eliza209]

I have a Biocube 29. I test weekly and do around a 4 gallon water change weekly. I switched salt (Reef Crystals to Fritz Pro blue box) about a month ago and my alk has dropped from a steady 7 down to 6. Calcium has remained between 420 and 440, mag 1485. I keep the salinity at 35. I use Salifert for testing. I tested my mixed salt water last week and found the alk to be 6. Someone said it could be the Fritz salt.

My question is, what do you use to raise alk when the cal and mag is stable?

 

[vetteguy53081]

I have a Biocube 29. I test weekly and do around a 4 gallon water change weekly. I switched salt (Reef Crystals to Fritz Pro blue box) about a month ago and my alk has dropped from a steady 7 down to 6. Calcium has remained between 420 and 440, mag 1485. I keep the salinity at 35. I use Salifert for testing. I tested my mixed salt water last week and found the alk to be 6. Someone said it could be the Fritz salt.

My question is, what do you use to raise alk when the cal and mag is stable?

Calcium is in a good range. To raise alk, you can use baking soda or soda ash

 

[Randy Holmes-Farley Verified Community Expert]

My question is, what do you use to raise alk when the cal and mag is stable?

It is possible that you only consumed alk (say, by having increasing nitrate), but it is also quite possible that you consumned alk, calcium, and magnesium in the normal proportions for calcium carbonate, since for an alk drop from 7 dKH to 6 dKH, you would not reliably detect the expected 7 ppm drop in calcium and the less than 1 ppm drop in magnesium.

If you do not need such additions frequently, it doesn't matter much whether you add calcium or not, but just don't conclude calcium is stable while alk is declining from this data alone.