How much backflow can I expect from a 220?

[Vapour1ze]

If power fails, on a standard 220 reef ready dual overflow tank. How much water can I expect to back flow to the sump? (In gallons) Anyway to reduce this?

Thanks!

[RocketEngineer]

A good starting point is to assume 1" of display drop. For a standard 72"X24" 220g tank, that works out to about 7.5g that will drain. The only safe way to reduce this is to have the return outlets close to the surface of the tank to ensure they pull air and stop siphoning as soon as the return pump turns off. Also, the height of the water above the lip of the overflow will impact how much drains from the display with a longer overflow pulling a thin film of water being the best option.

HTH,

[Vapour1ze]

A good starting point is to assume 1" of display drop. For a standard 72"X24" 220g tank, that works out to about 7.5g that will drain. The only safe way to reduce this is to have the return outlets close to the surface of the tank to ensure they pull air and stop siphoning as soon as the return pump turns off. Also, the height of the water above the lip of the overflow will impact how much drains from the display with a longer overflow pulling a thin film of water being the best option.

HTH,

Great. That does help. Thank you much! :)

[Cosmojo]

This helps with my 180 too, thanks Rocket!

[Toddrtrex]

I can try to do the math the next time I do a water change on my 210 (( dual overflows, with Herbies in each )). But, I was actually shocked at how little drains back into the sump.
I have my returns fairly high up, so that helps a lot. In addition having the main stand pipe about 5 inches from the top of the weir helps too.

Lastly, my sump is in the stand, so there isn't a ton of pipes to drain. A sump in a basement would increase things.

[ca1ore]

Yeah, it's tank width in inches x length in inches x height of water that drains down all divided by 231 to get gallons; plus whatever volume sits in the pipes. The best ways to reduce this volume is to either employ a longer weir or less pump volume to reduce overflow drain down; or move the return outlets closer to the water surface to reduce back siphon.

[Vapour1ze]

I can try to do the math the next time I do a water change on my 210 (( dual overflows, with Herbies in each )). But, I was actually shocked at how little drains back into the sump.
I have my returns fairly high up, so that helps a lot. In addition having the main stand pipe about 5 inches from the top of the weir helps too.

Lastly, my sump is in the stand, so there isn't a ton of pipes to drain. A sump in a basement would increase things.
Thanks, that would be awesome! I have a basement fish room now so I would have increased volume... I have a 93 display upstairs now. But am considering upgrading to the 220.... So trying to plan out if a sump upgrade is in store or not... I REALLY DONT WANT THAT TO BE THE CASE.

Todd if you remember, let me know I would appreciate it.

[ca1ore]

I can try to do the math the next time I do a water change on my 210 (( dual overflows, with Herbies in each )). But, I was actually shocked at how little drains back into the sump.

I agree, on my 265 it's about 7 gallons only.