I turned my sump into a cryptic sump. I used insulation around the sides and top to block out the light. I filled it with live rock most already had sponges and tube worms growing on them. I did this because I am running about 3000gph through my sump and was having trouble getting cheato to grow. I setup a 75g as a "marsh" tank with about 260gph going through it for the cheato. I will try to get pics of it sometime this week.