Skimmer floods every 3 days

[Savant]

So i have a Diablo XS200 that has worked fine for 2.5 years or so until about 2 months ago.
Now every 2.5 to 3 days the skimmer stops producing bubbles and the skimmer body fills up to the cup pumping water until the skimmer overflow switch turns it off.
Steps I have take that haven't worked:

plumbed skimmer intake airline to outside of the house
left the muffler open with no airline
placed cotton ball in intake muffler to act as filter.
removed cotton ball from intake in case it was somehow restricting air
moved skimmer water intake away from where ato water dumps in
ran with ato off in case ato water was somehow disrupting skimmer intake
set ato to only run once an hour to minimize number of water dumps
turned doser off in case 2 part solution was affecting skimmer
inspected venturi-no scale or clog
inspected and cleaned needle wheel-no debris or scale present
descaled pump several different times although very little scale on impeller shaft was present

i have actually only observed the skimmer flooding once as it has generally occurred between 12am and 6am but has occurred at other times.
When it is flooding the water entering the skimmer body has very few bubbles as if the air was restricted.
I have seen a similar issue occur (the lack of bubbles) without the flooding when there was residual oil introduced into the system when replacing old pvc with spa-flex (i failed to rinse the spa-flex thoroughly enough)

This is a basement sump, is it possible the oil furnace is somehow contaminating the sump (runs more in the middle of the night when its cold)? There is no issues with the corals in the dt

Is it possible the pump itself is the issue? I dont know enough about how a failing pump can affect the skimmer.

I am truly at a loss and the 3 day flood cycle has me completely baffled.

 

[Savant]

can a failing pump slow down over a period of time and resume full operation after being shut off and begin the slow down all over again?

 

[maxheadroom]

have you checked the venturi airline for cracks?

 

[slief]

One thing to consider when running the airline outside as you have done is barometric pressure and air density which changes from day to night. Those changes can have a big impact on skimmer performance and because of that, running your skimmer to the dry side may be needed.

Also, salt creep inside the Venturi port where the airline connects to the skimmer will also result in overflows due to restrictions in the airflow to the skimmer. I would suggest removing and disassembling the pump, checking the impeller for anything that might have intruded into it and also checking the port where the airline connects to it for any salt creep. If none of the above, disconnect the airline from the outside run and run the skimmer airline as it was intended and see if the overflows subside. If they do, then the issue is most certainly air density changes or environmentally related in which case, you will need to lower the water level inside the skimmer if you truly feel the need to draw air from outside.

The pump slowing down theory is unlikely as a pump that slowing down would reduce the level inside the skimmer as opposed to raising it. If the pump were failing, it likely would slow down and stay that way.

 

[mr_anderson]

+1 on checking the Venturi air in take. Check the hose or the part of the pump where the hose connects to the pump. Use a small toothpick or paper clip to remove the salt creep. This should be added to a 3 month maintenance list.

 

[Savant]

Thanks for the responses!

As part of the troubleshooting process I did remove the outside connection for the airline- it still floods
Many inspections of the venturi have never revealed obstructions/salt creep/calcium deposits. The nice thing about this pump is that the venturi ring is easily removed for cleaning and inspection.

I will carefully inspect the airline from the muffler to venturi looking for cracks however it is a very thick, soft and flexible tube so cracking is doubtful but you never know

 

[n2585722]

Flush that airline out with water while you have it off checking it.

 

[outy]

Ditch the cotton.

Run shorter airline.


No need for outside air.