sump qusetions

[rayviv]

I need to drill holes in the return lines and not sure what size. These are the lines that deliver the water from tank to sump over the floss. I hope to be running two pumps at between 500 to 700 gph on each.

Also need to drill holes in the skimmer return line in a way that will spin/roll cheeto in sump. Any suggestions?
Ray
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[TechGuy]

Holes for the returns to break the siphon in a pump failure? Mine are 1/8", and work fine. Drill them just below the water line.  They make a pretty loud noise too, my little alarm

[rayviv]

Thanks TechGuy,  I was actually talking about the line that sprays over the floss returning to the sump. I'm a newbe at this and still get the names of things mixed up. But I'm glad you reminded me of the siphon hole.                               
  Ray               

[TechGuy]

Something to consider, and very important. The volume of water that will be removed via syphon in a failure. The Volume in the plumbing, the amount of water above the holes in the returns all that stuff. Depending on your tank size this could be huge. For me its about 1.5G. I built mine, and didn't think to much about it. I have to run my water about 2" above the pump to accommodate for this. I made the baffle on the return side to close to the pump. So I have to top off 2-4 times a day to keep everything going.

The inlet side, from the tank is normally 1.25-1.5" ID hose for most overflow boxes. Not sure about the pre drilled stuff.

[rayviv]

And Thanks Again!