Water level keeps changing in return section of sump

[PDR]

Before we start I want to note that I am a complete noob when it comes to plumbing, so please bear with me.

I just added a sump (20 long) to my frag tank and I am having issues with the water level changing in the return section. I am running an eshopps pf300 hob overflow with a sicce 1.5 return pump.

I was originally planning on adding an emergency drain to the overflow and using a gate valve on the return line to silence the overflow. I was modeling it after my reefer 350 plumbing since I know that works.

My question is that depending on where the gate valve is adjusted, the water level will (sometimes, see below) raise or lower in the return section of the sump, but only a fixed amount, say 1-2" either way then stop. The weird thing is if I unplug the return pump for a couple of minutes then plug it back in, the return section will be a different level, as much as 1" off of where it was when I unplugged it.

I also have noticed when playing with the adjustment on the gate valve, that the water level will be different at the same adjustment. Example: I open the valve all the way and the water level is 2" below the baffle. I close the valve to get the overflow silent and it may raise 1". I open it back up and it may or may not drop back to the original level (2" below the baffle). I close it to silence the overflow again and it may or may not raise again.

I know that may sound confusing, but long story short, I have no confidence in using the gate valve as it would throw my ato off. Am I missing something obvious or is this normal?

Any explanation/help would be greatly appreciated!

 

[ArowanaLover1902]

Some pictures might help

 

[joec]

Your return section will change, lower, that's where evaporation shows up.

With regard to levels changing when you turn the return pump off and then on, I'm wondering if one of you baffle seams might be leaking water depending on flow pressure?

 

[jduong916]

If you have a skimmer the return section will fill with the additional water when the power is cut off. If you don't have a check valve after your return pump the water will siphon back from the top when the power is cut as well. There is also water in the drain pipe that will be in the sump after the power is cut.

I wouldnt worry about the change in sump water level when the power is off. As long as it stay the same while running, but to maintain this you need an auto top off.

Edit: also check if anything can block the return pipe, if something is in the way like a snail cruising over the drain pipe this will cause a water level change. I have a huge see hair and when he crusises over my baffles i lose half the water in my return section and gain about half an inch in the tank lol.

 

[PDR]

Some pictures might help

I will get some pics up later this afternoon.

Your return section will change, lower, that's where evaporation shows up.

With regard to levels changing when you turn the return pump off and then on, I'm wondering if one of you baffle seams might be leaking water depending on flow pressure?

These tests were done within an hour so evaporation was not an issue. I don't think any of the baffles are leaking, could be wrong though.

If you have a skimmer the return section will fill with the additional water when the power is cut off. If you don't have a check valve after your return pump the water will siphon back from the top when the power is cut as well. There is also water in the drain pipe that will be in the sump after the power is cut.

I wouldnt worry about the change in sump water level when the power is off. As long as it stay the same while running, but to maintain this you need an auto top off.

Edit: also check if anything can block the return pipe, if something is in the way like a snail cruising over the drain pipe this will cause a water level change. I have a huge see hair and when he crusises over my baffles i lose half the water in my return section and gain about half an inch in the tank lol.

I'm not worried about the change when the power is off. The problem is once the power is turned back on, the level is different from what it had been just a couple of minutes before. I do not have a skimmer.

 

[KStatefan]

I will get some pics up later this afternoon.



These tests were done within an hour so evaporation was not an issue. I don't think any of the baffles are leaking, could be wrong though.



I'm not worried about the change when the power is off. The problem is once the power is turned back on, the level is different from what it had been just a couple of minutes before. I do not have a skimmer.

Where else is the water level changing?

 

[PDR]

After about an hour of testing, I finally figured out what it was and (shocker) it was my own dumb falt lol.

I forgot I had put this as a temporary shim to raise the water level in the display.



When I was adjusting the gate valve it was slowing working its way off of the rim on the tank down to the lower lip, hence, the differing water levels whenever I messed with anything. ;Facepalm

 

[ArowanaLover1902]

Ha ha ha, happens to the best of us

 

[PDR]

I spoke too soon. While removing the shim did help with some of the crazy problems I was having, I am still having issues with an inconsistent water level.

I will try and explain what is happening and include a picture to help. If I turn off the return pump, wait a few minutes, then turn it back on, the water level in the return section of my sump drops about 1/8" consistently every time. I have done this multiple times with the same result. It doesn't matter if the gate valve is fully open or partially closed, it still does it.

Top mark is where the water level was before turning the pump off. The bottom mark is after turning the pump on/off 3 times in a row (I waited 5 min after turning off to turn back on, and 5 min after turning on to turn back off).


It's a good half inch lower, all in the space of about 30 minutes, the only thing that was touched was the plug to the return pump. I also marked the water level in the hob overflow and it remained constant throughout the test. I checked for leaks and found none. I usually turn my return pump off 2x a day for feeding, so over the course of a couple of weeks (my wc schedule), I could see this messing with salinity once my ato is up and running.

Does anyone have any idea why this could be happening?