Fluctuating water level in overflow compartment

[DjPhato]

Hi all, since I started the tank I noticed that the water level in the overflow compartment is fluctuating a lot. I have an herbie overflow and attach a picture here with a sicce syncra 6.0 as dc pump return.
I started with the return drain valve at certain position and pump at 16% but I needed to open a bit more the return valve many times. Basically every few days I notice that the level of the water in the overflow is rising and I open the valve a tiny bit to readjust the level. Why is this happening? I was expecting to find an equilibrium…tank is running since few weeks now. First time using herbie, any suggestions?
Main drain is the one with the valve, emergency is the one without valve.
Thanks

 

[kfisc]

My experience with a number of overflows is aligned with just that kind of variance. If the return and tank flow levels remain steady and is not prey to unusual evaporation conditions in your home, it winds up being its own idiosyncratic pattern. I'd worry if the overflow actually started to seriously dwindle or stopped.

 

[kharmaguru]

Hi all, since I started the tank I noticed that the water level in the overflow compartment is fluctuating a lot. I have an herbie overflow and attach a picture here with a sicce syncra 6.0 as dc pump return.
I started with the return drain valve at certain position and pump at 16% but I needed to open a bit more the return valve many times. Basically every few days I notice that the level of the water in the overflow is rising and I open the valve a tiny bit to readjust the level. Why is this happening? I was expecting to find an equilibrium…tank is running since few weeks now. First time using herbie, any suggestions?
Main drain is the one with the valve, emergency is the one without valve.
Thanks

As the system accumulates some biofilms, etc. the drain flow is going to change. The water level should be set to brimming on the emergency overflow, then if it rises slightly it trickles down the overflow a bit more but essentially remains unchanged in the overflow box. It's normal to have an adjustment period but you'll eventually land on the right setting.

 

[Vinny Kreyling]

The drain line should NOT be more than 2" below the water level in the sump.
The emergency should be above water level so you hear it if something goes wrong.

 

[DjPhato]

I understand that some biofilm might form but i was unsure if in few weeks this would be enough to cause a flow restriction and water level to raise. However, if you guys experienced it and say that should stabilise a bit more, I will wait and see

 

[DjPhato]

The drain line should NOT be more than 2" below the water level in the sump.
The emergency should be above water level so you hear it if something goes wrong.

Yeah I thought the drain was too deep in water and might be the cause of the water level issues because of the water rebound in the sump, so I did shorten it but didn’t help. Emergency drain is not above water level, but I tested it and its very loud

 

[kharmaguru]

I built and run a Herbie based on this article for years now and I've only needed to tweak the adjustment a handful of times. I love it.

Herbie Overflow Plumbing Guide for Quiet Reef Aquariums - gmacreef