Sumps & flooding

[Ocicat]

I have been looking at 125- and 180-gallon MegaFlow tanks from All-Glass, with the built-in overflows. According to their little diagram, the water doesn't just "overflow" over the top of the overflow, but it is allowed into the overflow through three locations in the plastic at varying heights —a slit in the bottom, a slit in the middle, and over the top. I saw mention of flooding with sumps... and it seems to me that using this design, if the power went out, the water would just keep pouring through those slits and totally flood the sump and then your floor, not to mention totally draining the tank. Is there something to prevent his, aside from installing a whole backup battery system?

Aren't there overflows that only take water over the top (as opposed to through slits lower down), so that if the power went out the water would stop draining once the tank level is so low it won't reach the top any more? Are these better?

TIA!

 

[gfishguy56]

I have the Megaflow 125 and i've had no problems with overflows or floods at all when i shut off the pumps or the storms down here do it for me. It's a wonderful system.
I do have it draining into a 30gal rubble/tufa/base rock sump, and the main sump as well.
I also have my piping rigged so it can drain into a 3rd sump, when i'm ready for it.
Maybe, it's overkill, but it works for me.
i gues my point is, get the Megaflow, you won't regret it.

 

[Ocicat]

Why doesn't it flood, when the pumps are off? What stops the water from continuing to drain into the tub below while the power is out and there is no pump pushing it back up? (Forgive me if this is a stupid question -- I'm right-brained!)

 

[20 20]

The overflow 'housing' is actually two separate pieces. The outer blank 'tube' is the one that has the slots for the water to enter from 3 different levels. The inner 'tube' is solid, so all the water that flows though the outer tube must flow over the top. So, the tank can only drain to the top level of that inner 'tube'.

 

[AndyH5512]

I have the 120 MegaFlow, and I love it! No problems with flooding when I shut it down for maintenanace, or when the power fails. Built in overflows are so much nicer than the hang on the back variety.

 

[ellisz]

When the pumps stop the water will drain till it reachs the top of the inner chamber of the overflow. There are slots down below but that water has to come up before it actually drains to the sump.

That is why you have to make sure the sump can handle the amount of water that drains from the overflow when pumps are off. There is also a siphon break on the return line to keep water from draining back into the sump from that point. This can happen. Some people forget about that one.