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.

 

[Cdentata]

I also have a CS90 and have had issues with noise. Generally, it is very quiet; sometimes when it is noisy, adjusting the vent tube helps but not always. If I add a Durso or modify the box's standpiipe with a pvc T, would I replace the standpipe cap with the T? Do I need to add an elbow to the T with it turned down so the open end is in the water? Last, do I need to put an end cap on the top of the T with a hole in it to allow air to escape or for the vent tube? I have read that that Durso's can help with noise but not sure if I understood how to make one. Thanks.

 

[wvned]

I also have a CS90 and have had issues with noise. Generally, it is very quiet; sometimes when it is noisy, adjusting the vent tube helps but not always. If I add a Durso or modify the box's standpiipe with a pvc T, would I replace the standpipe cap with the T? Do I need to add an elbow to the T with it turned down so the open end is in the water? Last, do I need to put an end cap on the top of the T with a hole in it to allow air to escape or for the vent tube? I have read that that Durso's can help with noise but not sure if I understood how to make one. Thanks.

I cant tell what you have there.
OO Ned Art

A durso traps the sound a drain is making inside it. The sound is made by falling water crashing into water at the bottom. The small hole that lets air pressure out so the drain will not pump air is the only place noise can escape.
You also get noise if the distance from the water level at the weir to the water level in the overflow is too great. Same reason. Water crashing into water.
I found a nice picture.

That stuff about the size of the hole determining the height of water in the overflow is bunk. Do not do that. Yes you can slow the flow down with a small hole. That means the air bubble in the overflow is bigger and blocking the pipe some. I just adjust the height to be correct. Something you just get right and it stays that way forever.

 

[Cdentata]

Thank you for the clear picture.

I wrapped the drain tubing coming out of the box with some insulation, which made the overflow much more quiet. So, it does seem to be a water flow dynamic. I have noticed that the 16 inch length of tubing from the bottom of the box to where it makes a 45 degree turn to go to the sump, is not completely filled with water; so, there is some turbulence at the turn. If that turbulence is causing the noise, there isn’t anything I can do about it as this is a physical limitation of my setup.

If I understand correctly, the CS90 box is quite dependent on the Aqualifter to maintain the siphon whereas the siphon for the Eschopps box seems to be directly dependent on the return pump to pull the water through the box. When I turn the system off, including the Aqualifter, to do a water change, I sometimes have a problem getting the flow going. It seems like an air block develops in the airline going through the Aqualifter.

Any thoughts on my practice or changing to the Eshopps box are appreciated.