Nitrate Problem

[seasalt101]

cc is very jagged and can wound the critters underside that is why you were having no luck get rid of the cc or you can vacuum a 1/3 each time you do your water changes the following week vacuum the adjoining 1/3 the following week the last 1/3 then start all over 1-2 clams should be plenty

 

[petjunkie]

You can change out all the substrate at once, that's how most people do it and how I did it and I also did a 40% water change at the same time to combat any hidden nitrates. Bacteria is in the live rock, not the water so as long as all the parameters are the same it shouldn't cause any problems.