Dual Overflow to sump.

[Ndev]

Hi All,

Firstly apologies for the awful drawing, but I wondered whether someone could help in advising whether the below concept would work/ would be useful for a overflow into sump.

I am looking at doing a project for a monster Reef tank and what to be able to draw from the bottom as well as the top. Would the below work?

The plan is to have a pipe drilled into the bottom (perhaps under a bottom grid to draw the dirty through the substrate) if this comes out of the tank and up to the same height as the top overflow then when the water level increases both will flow over at the same rate to remove the excess.

If there are any other suggestions / designs it would be great to hear.

 

[tomomothy]

The main obstacle I see at first is that if the green line ever breaks siphon and gets air in it then you may have a really hard time priming it to siphon again. You might be able to get around that with a valve open to air that can open to displace air and close to allow vacuum. That would only be possible if the green line doesnt tie in to the red line or if the red line is always under siphon as well. Id do them seperately. Other than taht it could work, but I imagine youd have a lot of gunk building up int he lowest point of the green line and it may eventually clog, so youd want to be able to remove that to clean it out too. Also keep in mind even with siphon achieved if your water level in your tank drops you probably wont have water flowing through the green line any more

I think your best bet would be to just have the green line come straight down and have a valve to regulate/stop flow. Or better yet, do away with that idea and have a power head circulate on the bottom of your tank. I tried it and it cleaned my substrate up, kicked all the junk up and cleared my tank in a few hours. Never been clearer

 

[rotccapt]

that design does work although the bottom overflow does not flow nearly as much water as a surface overflow. on my 300 gallon fresh water tank i have a single 1" dorso overflow at the surface and it flows more water than the 1 1/2" bottom overflow. now i did have it run the entire tank at about 600gph and it does work, but i had a working volume of water of about 30 gallons. this means that when i shut the pump off i get 30 gallons of water that drains down to the sump before the tank stops draining. this gave me about 4 inches of usable water in my sump. so i compromised and i installed the internal surface skimming overflow so that now i only have about 10 gallons of water that flows to the sump with the pump off.

so yes the design does work but it must be vented to prevent a siphon or you will drain your entire tank if the pump quits.

 

[guanl23]

Separate the drains into separate pipes set at the same overflow height so they are both vented and allow you to increase your gph later on?

 

[Ndev]

Maybe separating them is the best idea. I also considered having the bottom ons as a direct drain with a valve. That way no need to syphon, just open the valve for x minutes and then flow in x amount of new water into the sump. If I combine this with a power head on bottom in the opposite side of tank then I will get the advantages of consistent top skimming as well as removing all the muck on the bottom when water changing. Thanks, just want as little piping and excess as possible.