Thanks for all the great info. The tank is drilled on the back right side with an overflow. However, I expect with the upgraded return pump the overflow might be too loud (I took out the filter long ago claiming it as a nitrate trap). Since I have to empty the tank anyway when I insert the new sump, I think I may have to replace the overflow with a wider one (more room for the Durso) and look into a Durso. Two more questions:
1. Where can I find an overflow to glue into the tank?
2. I have not been using RO/DI water. Once I get the RO/DI set up, should I continue to run it as fish only for awhile to leach out the metals?
3. Ok, three questions - I have no idea how to set up the RO/DI filter. The tank is not near a water source. I wanted to set up something near the deep sink that could fill a 5 gal bucket for water changes. Not sure how to start this.
Once again, thank you for all of the info. Frank