Return pump siphoning when power is out

[Kenneth Hooper]

I have a 75 Gal tank with a 20 Gal sump/refugium. I just discovered that when the power goes off, the return pump begins siphoning water back into the sump.
Needless to say, 75 doesn't go into 20. It goes into 20 and the carpet.
The return pump is in the sump with a 3/4" hose going to 3/4" PVC up the outside of the tank and over the rim for the return.

Thanks in advance.

Ken

 

[Brad Miller]

What you could do...either one of these would work by itself

Install a check valve in pump return line
Raise the return as high in the tank as you can so it can’t siphon much out
Drill a small hole in the return line just under the water surface so it will break the siphon at that level

 

[SMSREEF]

As soon as air gets into the line, it will break the suction. The higher the return nozzle is in the tank, the less water to siphon.

If you are 4” below surface, that’s a lot of gallons. Right at surface of 1” under, not as many.

After you change depth of return, I would test and turn power off to see how many gallons are suctioned into the sump.

If too much, raise the return even more, or get a bigger sump.

 

[LIreefguy]

Like others said just raise return pump outtake line. Once it reaches air it will no longer siphon into the sump

Easy fix

Also why isn’t your output line hitting the surface anyway the air exchange is good for the tank

 

[Auquanut]

I drilled a small hole in the bottom of each of my returns right where it enters the display. That way, when the power is off, when the water level goes below the level of the return tube, the siphon is broken no matter how low in the tank the nozzel is. You get just a little water coming out of the hole, but you don't even notice it. Hope that makes sense.

 

[Sailingeric]

The small hole does the trick. I did two just to be safe.

 

[W1ngz]

The best choice would be to have the return outlet at less than 1" below the surface. Loc-line flare nozzles are great for this as they let you tuck the outlet just under the waterline, and it will suck air almost immediately when the pump goes off.

You could drill some holes as stated, 1 inch or less below the surface, but then you have to remember to clean them out. Also, 1 hole + 1 snail = water on the floor.

Never rely only on a check valve. Great for limiting the backflow or siphon during routine maintenance and feeding, terrible safety device unless you clean it bi-weekly. They get plugged up and let water through after just a few weeks.

 

[Aardvark1134]

To put it simply it is plumbed incorrectly. There are lots of videos out there on how to plumb a sump so that will not happen. Watch some of them and you should be able to find which mistake out of 4-5 common ones you made and fix it. NOTE: a check valve is only a bandaid as given enough time it will fail and you will end up with the same issue. BRS has some good plumbing videos.

 

[Kenneth Hooper]

Also why isn’t your output line hitting the surface anyway the air exchange is good for the tank

I have a very strange aquarium that I purchased used.
It is an AIO with a 3"x40"x21" back area for the overflow/return. The overflow, heater, bio-balls filtration and the return pump is located there and returns the water to the BOTTOM of the aquarium through holes along the bottom of the back overflow. I can only guess that the tank was designed for bare-bottom or freshwater and the setup prevents detritus from gathering on the bottom.
For a reef tank, that doesn't cut it. I have a sump so while the overflow comes from the back filter area of the tank, the return goes directly into the display area of the tank.
Since it is designed so that the water level in the display remains constant, the water would have to drain from the filter area before the level in the display started to go down. That would be 10 gallons draining into the sump before the siphon broke. Plus 5 gals in the ATO going into the 20 gal sump.
Too much.
That's why simply breaking the siphon won't work in my setup. (I've been tempted to buy a 75 gal from Petco during their $1/gal sales to replace my display with something 'normal'.)
Using a check valve on the return line may be my best bet, but it would need to go on the output side. I thought that it was "supposed' to be on the intake side to prevent damage to the pump but I guess it really wouldn't matter.

 

[Aardvark1134]

AIO aquariums are not made for sumps what you have is AIO that someone tried to drill for a sump. Never heard of any brand that would do in AIO with sump as that completely and totally defeats the purpose of the expensive AIO setup.

 

[Bayareareefer18]

75 AIO? That's interesting.

Are the holes in the bottom of the overflow bulkheads? If so stick some pipes in those babies and bring the returns up over the top

Photos would help

 

[Kenneth Hooper]

The AIO design of this tank is impractical. It is made for bio balls only - I removed a copy paper box full of them - easily 500 or more. Also, it fills the tank from the bottom giving little flow in the tank unless you are resting on the bottom in the back of the aquarium behind the landscape. With the return exiting at the bottom, the sand is in constant turmoil. It is unlike any AIO design I have ever seen or heard of.
There is no place for a skimmer hookup in the AIO. Also, I want the added benefits of a refugium set up feeding the DT.
The tank has never been drilled. The return is from the outside of the tank and the overflow is handled by a HOB overflow box.

 

[DuckSlayer627]

Pictures?

 

[Aardvark1134]

Bio balls are easily replaced with matrix or marine pure, Carbon, filter pads, purigen and anything else you want to use will also fit where the bio balls were. You can even put reactor media in fine mesh bags right there in the trickle bio area. While I agree bio balls are useless...the chamber for them is amazingly useful.

 

[KStatefan]

I am sure there is a solution. Post some picture of the setup lots of smart people here to help you figure it out.

 

[jd371]

I drilled a small hole in the return just under the water surface. If that gets clogged for any reason the return nozzle is pointed towards the water surface as a secondary siphon break incase the first one fails.
Ooops! just read through the whole thread and you have a funky set up... pictures would help get an understanding of what you're dealing with.

 

[Saltyreef]

The best choice would be to have the return outlet at less than 1" below the surface. Loc-line flare nozzles are great for this as they let you tuck the outlet just under the waterline, and it will suck air almost immediately when the pump goes off.

You could drill some holes as stated, 1 inch or less below the surface, but then you have to remember to clean them out. Also, 1 hole + 1 snail = water on the floor.

Never rely only on a check valve. Great for limiting the backflow or siphon during routine maintenance and feeding, terrible safety device unless you clean it bi-weekly. They get plugged up and let water through after just a few weeks.

Yep. I plumbed my system double redundant with a check valve and the locline flare nozzle just under the surface.
Until my check valve stopped closing cause #noclean.
Removed it and no issues with the sump flooding. Siphon breaks immediately since I have one corner of each return flare nozzle breaking the surface ever so slightly. So glad I did it right the first time LOL. No holes needed.

 

[drivingmecrazy]

I agree with drilling the small holes to break the siphon. But I have found that this can be another problem later. Keep an eye on the holes and make sure algae, or any coraline algae does not grow over the holes. Otherwise your return pump, will be siphoning water once again on another day.

I like check valves but I learned those can fail to due to faulty design, or snails/ livestock getting stuck.

I would recommend gluing small screen over the intake just to make sure no critters can enter. I personally like the plastic pvc drains in plumbing for houses.
I cut a small piece and glue it.

Both or all three is better.



How much we learn!

My wife can agree I am a expert on making water hit the floor somehow someway I use to tell her this mistake won't happen again because I learned from it) and a few weeks later I'll make another different mistake

One of the challenges I like about this hobby.

 

[Aquariumaddictuk]

I drilled a small hole in the bottom of each of my returns right where it enters the display. That way, when the power is off, when the water level goes below the level of the return tube, the siphon is broken no matter how low in the tank the nozzel is. You get just a little water coming out of the hole, but you don't even notice it. Hope that makes sense.

This old post has solved an ongoing anxiety inducing problem.thanks for a great tip!