This might be tough but I want to add a 75 gallon sump to my current 35 gal sump.
I want to put 10 inches of sand or sub straight to one side and rubble and green to the other side.
I think if I put clean sand in there it will not spike my ammonia or nitrates.
Any thoughts?

I have 300 gal. tank running for a year in the current configuration. I have 500 lbs of Live Rock, 30 or so fish, with minimal coral.