[duster]

I'm in the planning stages of a 40g with all equipment to be placed under the tank, including a 20g sump. This will be my first system with under-tank plumbing and I am wondering about the possibility of a sump overflowing in the event of a power outage or pump failure, if I am not home to shut off ball valves. If the pump that runs the sump shuts down, will water from the main tank drain into the sump until the water level in the main tank is below the bulkhead fitting? If this will happen, is it advisable to drill the bulkhead fitting supplying the sump near the top of the main tank? Can a float valve be rigged up in the sump to close off the supply line? Any diagrams, parts lists, instructions, etc. to accomplish this would be much appreciated by this newbie.

[kissman]

what I did was filled the display tank until water started draining. Filled ther sump just above the pump. Turned everything on let it cycle little. Then I cut everything off. I let tank drain back into the sump. When it was done I filled my 20g sump just below the top and cut everythng on. When the tank fills back up you will have room for the power goes out. Also you can drill a hole in the pipe that runs into the tankl from the sump and it will break suction and not drain as much.

[duster]

Do you use hang-on-tank overflow skimmers to siphon water into your sump or is your tank drilled? If it's drilled, are the bulkhead fitting(s) that siphon to your sump placed low or high in the main tank?

[kissman]

My tabk is drilled the bulk heads are high in the tank. Drill a hole just below the water level using a drill bit in the return line. Does not matter if drilled or overflow I have used both.