So I have started getting the pool ready for the warm weather to come and I want to address the gap I currently have in between the retaining wall and the pool. It varies but averages about a foot from the pool and is 6 inches deep. The retaining wall was put up during the winter so I didn't bother filling that area when it was put up. The pool company said they always recommend mulch, because I guess rock can put too much pressure on the pool wall. I don't understand because I am pretty sure the model of pool I have they also said could be buried up to 2 ft (which they didn't do even though I requested it, but I digress...) so I would think some pressure on the bottom of the wall is fine. I like the idea of rock better than mulch because of no maintenance but the pool company's suggestion has me hesitating.