Carbo calcium problem

[lelandmarine]

I was filtering gravel yesterday in my sump and I noticed right below where the carbocalcium drips into the sump twice a day (only have been using carbocalcium for about 3 weeks) the gravel was rock hard. it was an area about 3“ x 3“. All of the rest of the gravel was fine . Do you have to have high flow with carbocalcium? Has anyone else had this happen? It was challenging to break it up by hand it was so concrete. I’m wondering if that would dump a lot of alkalinity and calcium into the tank when you break it up? Thanks

 

[GlassMunky]

Firstly, why is there sand in your sump?
A sump should just be a tank, without any sand so that you don’t trap detritus.
Secondly, yes, any alkalinity supplement can cause that kind of precipitation in sand if it’s localized.

 

[lelandmarine]

Thanks. So I have a bare bottom main tank. I have caribsea special grade gravel in the sump (in my case its easier to access the sump to clean and keep detritus from accumulating). I I haven’t had this with the other two parts or kalk.