DIY Sump Cooling Fans This is an excellent DIY for lowering your tank temperature a few degrees. I got the idea from the Melev's Reef website. So you may want to check there for a few more designs. I was a little skeptical at first wether it would work but after creating one and installing it on my tank, the temperature was lowered by about 3-4degrees. I bought the fans that have LED lights in them which I found on Ebay for about $4-5each. Materials: 2 - 90mm Computer fans Scrap acrylic pieces AC Adaptor Weld-on #4 or Silicone sealant Cooling Fan Construction 1. Measure the sump tank you will be placing the fans on. 2. Cut 2 - 2" strips of acrylic so that it will hang over the sump on both sides. 3. Cut a notch on each side of the strips so that it sits on each end of the sump. See Schematic (white pieces) 4. Meaure one side of the fans and cut two pieces of acrylic 2"xlength of fan+1/4". See Schematic (blue pieces) 5. Measure width of the sump from the inside and cut two 1/2" strips of acryic 1 inch shorter than thewidth of sump. These will be on the bottom of the acrylic box and hold the fans. See Pic.(red piece) 6. Using electrical tape, tape the pieces in place. Test the measurements by placing a fan in it to see if it fits snug. 7. Use Weld-on #4 or silicone sealant to bond it all together. 8. Allow 24 hours to dry. 9. Wire your fans to an AC adapter and place them in the box so they are blowing downward. 10. Place the box in your sump. Done!!