Fluctuating water height (I GOT IT!)

Hey everyone. I just recently set up my ATO and have been having issues. (Only noticed because i hooked it up) I checked the sump and the return chamber and the water was about an inch above the float switch but the ATO pump was not running. I turned the switch to the ATO off. I let the evaporation take care of the high water. Today I turned the ATO on and let some water in. I did that only for 1 minute because I notice the water level dropped after I turned it on. I thought it was weird. I sat there and watched the water level in the return section for about 30 min and countless number of times the water level dropped, only about half an inch and then raise up again. That half an inch is enough to let the ATO kick on and fill. When the water level comes back up it shuts off the pump but continues over the switch. For the life of me I cannot figure out why the water level is lowering and raising.
If anyone has watched their return section do you have a fluctuation in your water level? I just figure this out.

 

That section "should" be stable. Maybe your over flow needs adjusting and it's allowing water to build up in the pipes? its a long shot but my only guess~

 

I don't think your return should fluctuate that much unless you have a standing wave in your tank from a vortech. That would cause more/ less water to flow down the overflow at any given period (depending on when the waves hit the overflow) which may cause your return section to fluctuate, as your return pump will pump at a constant speed.

The other question is what type of ATO do you have? I have a JBJ and I know there are multiple modes and one of them uses two switches, one to turn on the pump, one to turn it off. It may be a similar case for you, except that if you don't have the second shut off sensor, it will just keep filling.

Pictures/ descriptions of your tank and equipment would greatly help in diagnosing the problem.

 

That was my thoughts that the return section should not fluctuate.
I have an overflow box with 2 u tubes and 2 stockman stand pipes. My return pump is a little giant 4 mdxsc. View attachment 57587
This is the best picture I have of my overflow.

I do not have a vortec and there is no wave in my tank. My ATO is a DIY ATO. I have it shut off because I don't have a second switch set up for high water.

I think it's my overflow but I just don't know for sure.

 

It's one of two things, but I suspect the first one I'm about to list due to a HOB overflow.

1) Your overflow is a bit variable, causing the water level of the DT to change slightly (doesn't take much; it would be magnified in the return chamber). This could be caused by a few things, but namely the suction of a HOB changing. A drilled tank wouldn't experience this, unless the standpipes were designed poorly causing the water level in the overflow box to vary. But you could be facing that problem also.

2) Skimmer fluctuations. The water level in your skimmer will change a bit as it operates, as the amount of dissolved organics varies.

 

Picture did not come through. I also think you check that your overflow is not changing to a siphon at times. This could cause this type of reaction.

 

Hopefully that one worked.
I don't notice the DT volume changing but it's a 125 so a slight amount wouldn't show. My standpipes do no show any signs of syphoning.
Is there any way to get this to stay constant or with the hob overflow am I always going to have this?

 

is the tube that provides the water from the ATO under the surface in the return??

This may cause the water to be siphoned back out, to the ATO. then triggering the pump to push it back to the return, creating a little filling/draining cycle.

The float goes down...pump comes on...float goes up....the pump stops....water siphons back out....pump comes back on. repeat

 

No, the ATO line is about 1-2" above the WL.

 

Dan?,

On my system, my ATO is no where near my skimmer, DIY HOB overflow.

My DIY ATO, (an ATO is an ATO- it should ATO- right?) is in the part of my DIY sump that is near my return pump.

My skimmer is in it's own DIY compartment in my sump- which stays pretty constant too.

Sorry I missed it, but where do you have this valve for your ATO pump again? (mine has no pump- another thread)

If it is, I feel it should not be in the HOB return area- but an area of the sump that is more stable, and make the adjustment there for your system to have a good, constant water level.

When I watch my DIY intank overflow (works on a DIY HOB siphon) at times the water level inside the intank part fluctuates, but not my DT, or the other chambers of the sump.

I hope any of that helps

Keep on Reefiing

FYI, I also have a High Water Return pump cut off switch on my DT- so I never have the Family Room marine water flood - that I've never had!
I felt this was good insurance for a siphon style overflow. Murphy's law