Water Level In Overflor Box Slowly Rising

[cm11599ps]

For the past month or so I've noticed that the water level in my overflow box rises slowly over the course of a few days. When I start my return pump there's maybe 5" of water in there. After a week or so you can see about 7" of water in the overflow box.

Once the water level rises I turn the return pump off and turn it on a bit later. When the pump comes back then the water level in the overflow box is low again but gradually rises during the next few days.

I've throttled my return pump back and it helped but it's still happening. Any ideas?

[USC-fan]

You have a utube box?

You are getting air in the tube. Shake it very hard once a week.

[bennr]

What type or model of overflow/prefilter are you using? If it is slowly pulling less water over a few days I would guess air bubbles in the siphon tube are building up over time......can you provide more info.....like models of prefilter box, return pump, hose size and how it is run and length, did u mod prefilter in anyway, how far open is control valve on return pump? I run two prefilters on a mag 18.....have always used prefilters and know quite a bit about them.....good and bad experiences lol.....

[cm11599ps]

I'll try that. Yes, a u tube. Tanks been up since march and it's only recently this has happened. Thought I had a snail in the line but it looks clear.

[cm11599ps]

It's a life reef setup running a mag 9 I believe. I believe it's 3/4" return with 1" drain. Sump under tank with no weird turns or kinks.

Return pump tees into a fuge and the return was at 60% or so. About 6 weeks ago I opened her up all the way and perhaps that's when my problem began. Hard to remember.

[cm11599ps]

That appears to have been the problem. I took my u tube out of the water, run some airline tubing in the u tube, put the u tube back over the tank and sucked the air out. It's been running fine ever since last night. Thanks!

[USC-fan]

Next time just shake it very hard. Gets the air out.