Overflow water level keeps rising and falling

[plunderisley]

Hi all,

I have a 1000L reef tank that has been running for over 6 years now. Recently (a few weeks ago) I noticed that in the overflow, the water drops around 5cm and then goes up around 7cm, till it drops back to where it started and this continues on. I haven't changed nor added anything to the tank in a long time.

I'll post some photos, but I will also explain the setup and what I tried so far.
- First thought was the pipe in the overflow to the sump is dirty. So I removed it, cleaned it inside and outside and placed it back. Didn't fix the issue
- From the overflow (under the tank) to the sump, there is a ball valve that I use to dial in exactly the height in the overflow. I disassembled that whole setup and cleaned inside the ball valve (and checked if anything was stuck). Didn't fix the issue
- I replaced the pump. Didn't fix the issue
- I plugged the pump into my server's UPS to see if there is an electrical current issue. Didn't fix the issue
- I thought maybe the overflow pipe cap to prevent large debris flowing in might be dirty (or causing an air/water suction) so I removed it and just had the water flow directly into the unobstructed pipe in the overflow. Didn't fix the issue
- I adjusted the return pump flow out to see if it was pushing too much water and that could be the problem. Didn't fix the issue


At this point I'm stumped.
The water rises and lowers every few minutes and I can't figure out why.

 

[Vinny Kreyling]

DC Pump?

 

[wvned]

Sounds like a corner overflow with the air vent plugged up.

 

[plunderisley]

DC Pump?

Its a normal AC pump, but the UPS would be running on battery so it would be a very stable output.

 

[plunderisley]

Here are some photos:

 

[griss]

@BeanAnimal any thoughts here?

 

[kharmaguru]

Hi all,

I have a 1000L reef tank that has been running for over 6 years now. Recently (a few weeks ago) I noticed that in the overflow, the water drops around 5cm and then goes up around 7cm, till it drops back to where it started and this continues on. I haven't changed nor added anything to the tank in a long time.

I'll post some photos, but I will also explain the setup and what I tried so far.
- First thought was the pipe in the overflow to the sump is dirty. So I removed it, cleaned it inside and outside and placed it back. Didn't fix the issue
- From the overflow (under the tank) to the sump, there is a ball valve that I use to dial in exactly the height in the overflow. I disassembled that whole setup and cleaned inside the ball valve (and checked if anything was stuck). Didn't fix the issue
- I replaced the pump. Didn't fix the issue
- I plugged the pump into my server's UPS to see if there is an electrical current issue. Didn't fix the issue
- I thought maybe the overflow pipe cap to prevent large debris flowing in might be dirty (or causing an air/water suction) so I removed it and just had the water flow directly into the unobstructed pipe in the overflow. Didn't fix the issue
- I adjusted the return pump flow out to see if it was pushing too much water and that could be the problem. Didn't fix the issue


At this point I'm stumped.
The water rises and lowers every few minutes and I can't figure out why.

Does the water drop fast and then rise slow? That would be a clue that full siphon is coming and going and there is some kind of plumbing leak on the drain side.

Is the drop and rise just a gradual but equal up/down cycle?. That would be a clue that there is a problem on the return side - bad check valve, sump level pipe leak or some other floppy obstruction. I'd add voltage irregularity but you seem to have ruled that out.

 

[T Diddy]

There’s a restriction of flow somewhere…likely at the sump level. Back pressure builds up (water rising in overflow) so until the full release. Mine does the same thing. In my case it’s because I don’t have a large enough pipe to allow for airflow. Has your sump inlet pipe become partially submerged somehow?

 

[plunderisley]

To follow-up back here:
After a while it kinda stopped being such a drastic change that I kinda ignored it. Yesterday I cleaned the Ecotech MP40s wet sides and the problem started all over again. I looked at my schedule and the difference in water level do seem to change around the times that the different modes change in my schedule. It's very bizarre that a clean wet side can cause that much of a drastic change in the water level. I also don't know how to fix this other than lowering the max power of the powerheads...

 

[ironwill723]

Have you snaked your drain lines to check for obstructions or buildups?

 

[plunderisley]

Have you snaked your drain lines to check for obstructions or buildups?

yup, drain lines were cleaned out. That was one of the first things I did.

 

[wvned]

Are you pushing water toward the weir with the MP40?
That will change how fast the water enters the overflow and make the level change inside it. When the wetside gets dirty it will do it less because the wave maker moves less water.

 

[plunderisley]

Are you pushing water toward the weir with the MP40?
That will change how fast the water enters the overflow and make the level change inside it. When the wetside gets dirty it will do it less because the wave maker moves less water.

That makes sense, but I never had this issue before and I had the tank for quite a few years.
I can try moving the mp40 a few in in a different direction and see if that changes anything.

 

[five.five-six]

snails in the overflwo pipe?

 

[plunderisley]

snails in the overflwo pipe?

nope

 

[Vinny Kreyling]

A clogged powerhead really reduces flow in the water.

 

[plunderisley]

A clogged powerhead really reduces flow in the water.

Well yeah, but they weren't clogged (just dirty). I just clean them every 3months and remove some of the buildup so it shouldn't have changed the flow that much.