Above tank sump?

buzzojones · Jun 13, 2026

(Sorry this is a less wordy repost of a version I posted an hour ago but I didn't think it took) Due to space constraints I need to mount a 10 gal sump above my display.

Plan is to have two overflows down to main tank with a submersible pump up to sump.

Move all the equipment I can to sump. ATO in the overflow reservoir.

A concern is the pump somehow goes too fast. Would add a float sensor at sump to cut off tank pump if sump gets too high of water.

Any other issues? Is this doable and technically sound? Anything I am missing?

tbrown · Jun 13, 2026

So this would basically be similar to having a "Display Sump". Doable, yes. A consideration is that the water level in the display has to be low enough to accept the "extra" overflow water in case of any power outages. Same would apply to an under tank sump. The lowest tank in the system has to be able to handle the extra water when the power fails or you have to shut the pump off for maintenance.

As far as the pump, if you size the overflow from the sump to just higher than or equal to the pump speed the only thing you should have to worry about is the weirs staying clean/unobstructed. Also, the ATO would go to the display, not the sump.

buzzojones · Jun 13, 2026

Yeah, the sump could be considered a display. I would cover the front of ut with various BS. Good point on the extra water.

Could I put the ATO in sump? With a bottom sump I know you do but if this isn't possible in this configuration? i just hate having it on my main tank because the rim gets in the way of the cable and it always twists and moves and wanna get as much stuff out of it that I can.

CHSUB · Jun 13, 2026

Mine is what you are planning . I have a TLF valve to control flow to high “sump”

Uncle99 · Jun 13, 2026

The ATO must operate at the “ lowest” level in the system, regardless of what’s where.

Evap is only noticed at the lowest point, so any other place is a problem for ATO IMM.

UncommonSense · Jun 13, 2026

buzzojones said:
Could I put the ATO in sump?

The display tank would be the part of the system fluctuating in water height with this configuration, so the ATO sensor would have to go in the display (and might have long run cycles due to how much water volume is needed to appreciably change display water height)…

The ATO fill line can be routed to the overhead sump, but this sump will be at a continuous operating water height, thus cannot be used for your ATO sensor(s)!

tbrown · Jun 13, 2026

buzzojones said:
Could I put the ATO in sump? With a bottom sump I know you do but if this isn't possible in this configuration? i just hate having it on my main tank because the rim gets in the way of the cable and it always twists and moves and wanna get as much stuff out of it that I can.

As everyone else stated, the short answer is no. Display is where the level fluctuation will be seen.