[elkman97462]

I am setting up a 135 gal. glass tank as a fore reef, mainly for corals so I want a lot of flow. I am going to buy the glass hole overflow box set up in either the 1500 gal (2 each 1+1/2" outletls), or the dart (2 each 2+1/2 inch outlets) and drill the tank. Would I be better off with 1 Mag 18, or 2 Mag 7s or 12s? Either overflow will have twin outlets that I plan to increase to 2" to return to the sump. I have a 35 gal. sump. I plan to install a 1" spray bar on the bottom of the DT with a Rio 32S for movement. I read an article about using a system similar to the spraybar idea at the top of the tank with 1" pvc and 3/4" directional nozzles that I want to run the return line through around the top perimeter. I have about 54" betweeen the return pump placement and the top of the tank. I plan on running 2" pvc return and then reducing it to 1" with 2 each 2" 45 st ells and then 2 each 1" 90 ells into either a tee or maybe running each leg off its' own pump if I use 2 smaller pumps. Seems like redundency would be good in case one failed.
What do you all think? Thank you for your thoughts.

[pogodzib]

I always like having two return pumps incase one were to fail, one would still be working. I had a return pump fail after a power outage once and my tank went heaterless & skimmerless for two days. I didn't notice that it failed until a couple fish got sick due to 68 degree tank water. With that said, many people just stick with one return pump.