Past precipitation causing problems now. What to do?

[painter1982]

Around beginning of January I was having low ph issues after I transferred over to my new Mariner M130. I decided I’d dose soda ash for my alkalinity. That caused precipitation and I noticed it on my heaters and the substrate got a hard crust. I broke some up a few weeks ago and had an alkalinity spike. I wasn’t sure if I caused the spike at first. I broke some up yesterday and noticed the alkalinity climbing again. How do I take care of the hardened substrate safely? It’s an sps tank. My normal parameters are:
Alk 9.0 to 9.2
Cal 440 to 455
Mag 1400 area.
Ph 8.25 to 8.4
Phos .06
Nitrate 10
Salinity 35ppt
first stir of gravel caused Alk to 10.5 and calcium to 470
Now alk up to 9.4 today from stirring yesterday. Any suggestions?

 

[Randy Holmes-Farley Verified Community Expert]

Breaking up precipitated calcium carbonate doesn’t cause an alkalinity spike. It cannot dissolve in normal seawater.

But fine solid particles in the water will give a false high reading for alk as the particles will dissolve in an alk test.

 

[painter1982]

Breaking up precipitated calcium carbonate doesn’t cause an alkalinity spike. It cannot dissolve in normal seawater.

But fine solid particles in the water will give a false high reading for alk as the particles will dissolve in an alk test.

That’s good to know. I had noticed both times I broke it up that I had alkalinity rise when normally it stays 9 to 9.2 area. Thank you.