Siphoning? Please explain if this is correct

[110galreef]

Looking at the pic, left tank is the RO/DI holding tank.

This stands 28" high, the little box above the holding tank is an aqualifter pump. that is about 32" high.

The box on the right is my sump. top of sump is 20" off ground and the point where the outlet of the ATO pump is about 14" above the ground. The water level is about 12" off the ground
I have the aqualifter pump the water from the bottom of the holding tank. to the middle baffle. The water output is not submerged at all. The holding tank was about full and when I shut the pump off water still flowed. Siphon?

Is this right i was suprised that a siphon was created since the inlet for the pump is at the bottom of the holding tank. I figured since the pump was above the water line and the output was above the inlet, and the input was the lowest point i'd be ok....Guess not

Therefor, I am assuming the siphon would stop when the water in the holding tank reached the level of the green line?

The problem is resolved by moving the output of the pump to a high point in the overflow, which is above the holding tank., but don't really want it that way

Ideas?>

 

[dogstar74]

Yes it is a siphon that keeps the water flowing, the paddles in the pump slow down the flow when the pump is not turned on, but it can't stop the flow of a siphon, thus all the reservoir will empty into the sump if left to it's own devices.

The only way to stop this from happening, is for the reservoir to be lower than the sump, and have the sump end of the tubing not submerged. Then when the pump kicks off, the water within the line/pump will back siphon into the FW reservoir.

If you choose to have the FW reservoir higher than the sump, then it must be air tight and have two hoses that run to the sump. One set at the level of the desired water height in the sump the other submerged to allow inflow of the fresh water. There is no need for a pump at all!

I'll post a link to a thread describing this system.

Aaron

 

[dogstar74]

Here ya go

http://www.reefcentral.com/forums/showthread.php?t=2002384

There's a good explaination of the system in this thread.
HTH
Aaron

 

[dogstar74]

Therefor, I am assuming the siphon would stop when the water in the holding tank reached the level of the green line?

No, the siphon will continue even if the line from the Aqualifter is under water. The siphon will only stop when both water levels are equal.

 

[110galreef]

Ok, thanks.

Looks like i either need to run the line up to my overflow or build something like you!

 

[dogstar74]

If you wanted to keep the system the way you have it, due to constraints of stand space etc, then you can solve the siphon problem by putting a Tee on the outlet line at the highest point in the loop. Run one output line into your sump and the other output line into the reservoir. This will increase the time the pump needs to be on to fill the sump, but once the pump turned off, then the higher line would stop the siphon and allow the system to work like you desired it to.

 

[110galreef]

If you wanted to keep the system the way you have it, due to constraints of stand space etc, then you can solve the siphon problem by putting a Tee on the outlet line at the highest point in the loop. Run one output line into your sump and the other output line into the reservoir. This will increase the time the pump needs to be on to fill the sump, but once the pump turned off, then the higher line would stop the siphon and allow the system to work like you desired it to.

Interesting. I will give that a look too.

Thanks for the ideas!:lol2:

 

[psteeleb]

I had this same issue and fixed it by sticking a scrap piece of pvc pipe in my sump that was taller then the RO/DI reservoir. I then cut the tubing from the RO/DI fill pump to be long enough to stick inside the PVC pipe but above the water level of the reservoir

I may have a picture in my archives someplace

HTH

 

[110galreef]

That is a sweet idea!
You guys are awesome

 

[noahm]

You can also just put a T at the outlet and run a few inch piece of tubing straight up (so it is clearly the highest point), then run the rest to the sump. When the pumps stops, the siphon will break. The little snorkel will prevent any chance of dribble.