The middle chamber of my sump is where I keep my skimmer (insump model). If I remove the bracket holding the skimmer at the proper height and replace it with sand, do you think it will help with reducing nitrates, or do you think the footprint is too small to make a difference? One small issue I'm having is that it's hard to siphon crap from under the existing skimmer bracket, and removing the skimmer and bracket at every waterchange is quite the hassle. Nitrates are currently at about 30-35ppm (my own fault for not maintaining the tank as much as I should have). I'm back on track and looking for options on reducing nitrates. The footprint of that middle section in my skimmer is 12" wide X 18" deep and I'll be ablle to go as deep as 7", which should make for quite a bit of sand. The DT is a 90 g. My future plans (when it's within budget) is to purchase another skimmer that can be placed outside of the sump, and use the middle area for some chaeto and/or frags.