Planted Tank Guru
Join Date: Jul 2010
Location: British Columbia, Canada
If it's dense, good quality, quartz-based silica pool filter sand, and it's only @ 2" depth, the risk of developing any problem anaerobic pockets is extremely low, if not nil, - I wouldn't worry about it.
I've been using PFS for several years in my planted discus tank, and have never had any type of problem with it - it's a good substrate to use.
Even with play sand, at that depth, even though it compacts more, it should not be any problem.