Air suction on cartridge filter

cazten

Member
May 27, 2021
6
Gilbert AZ
New pool owner here. Was attempting my first cleaning on the cartridge filters and ran into a snag....

I opened the top bleeder valve and then the bottom drain (which has a hose valve on it). When I open the bottom drain on the filter housing it actually sucks air in! There seems to be slight suction pressure and when I crack the bottom valve air sucks in and I can hear the large air bubbles entering the filter housing. Considering water was supposed to empty from the filter I figured something is wrong.....

I havnt left it cracked open for more than a few seconds at a time, maybe 20 seconds max in total as I was thinking around. Any thoughts on this and how I should proceed?
 
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cazten

Member
May 27, 2021
6
Gilbert AZ
Pictures attached! The system looks like it's had better days.... I recently had the Salt cell and entire automation system upgraded. Everything else is original. The second water pump is for a water feature/slide.
 

Texas Splash

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Okay, so from your description it sounds as though once you opened the bottom drain and felt a suction you stopped right? You haven't actually disassemble the filter yet right? A are some things I would do/verify:
- Check those 3-way valves before the pump and after the filter. Those should be closed to prevent water from going to/from the equipment pad. In the pics it looks like one or more might be in the open position. You need those closed to isolate the filter and pump from the pool.
- Once you are sure that water flow is isolated from the equipment pad by closing those valve, go ahead and open the top air relief first and leave it cracked open. Then you can try opening that lower drain valve again to start letting the water out of the filter so you can open it up.
- While that's happening, you should also be able to open the pump (clear lid) to clean out the strainer pot.

See if that works for you.
 

cazten

Member
May 27, 2021
6
Gilbert AZ
Okay, so from your description it sounds as though once you opened the bottom drain and felt a suction you stopped right? You haven't actually disassemble the filter yet right? A are some things I would do/verify:
- Check those 3-way valves before the pump and after the filter. Those should be closed to prevent water from going to/from the equipment pad. In the pics it looks like one or more might be in the open position. You need those closed to isolate the filter and pump from the pool.
- Once you are sure that water flow is isolated from the equipment pad by closing those valve, go ahead and open the top air relief first and leave it cracked open. Then you can try opening that lower drain valve again to start letting the water out of the filter so you can open it up.
- While that's happening, you should also be able to open the pump (clear lid) to clean out the strainer pot.

See if that works for you.
Correct I did not pull the filter apart. I had thought about closing off the valves as well but it doesnt seem possible.

On the suction side there a three way valve that lets me choose between skimmer and drain but doesnt position in such a way to cut flow off completely.

On the pressure side I have a three way valve to choose between normal route and heater bypass but again I cant cut off flow completely

I turned the system back on and it took a solid 10-15 seconds before water hit the pump so we there was obviously some sort of vacuum effect draining water back out of the system once I crack the filter housing drain plug. Im not sure if I have any option other than letting it drain completely and then trying to prime the pump before turning it all back on?
 

Texas Splash

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Your valves look similar to mine. The handle end means open (water can flow that way), so turn the other (flat) side to the pipe you want closed. Do that for both valves, one before the pump and one after the filter.
 

cazten

Member
May 27, 2021
6
Gilbert AZ
Your valves look similar to mine. The handle end means open (water can flow that way), so turn the other (flat) side to the pipe you want closed. Do that for both valves, one before the pump and one after the filter.
Correct, it seems like maybe the valves were both installed backwards? I cant get them to turn to the direction which would close off the system completely. Pic attached with an example of the three different directions I can point the closed end at.

The attached pics shows the suction end where I can balance between skimmer and drain.... But full closing the system would require pointing the closed end of the valve at the inline leaf basket and it wont turn that far.
 

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cazten

Member
May 27, 2021
6
Gilbert AZ
I have a feeling this video just explained why I couldn't close off the common inlet/outlets... New three-way valve user here! I'll try it again tomorrow morning and see if I can get the valve to rotate further and block the required port.

 

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Texas Splash

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New three-way valve user here!
Ha ha. The video clarifies what I was trying to describe above. In the case of my own 3-way valve, the tech actually have me just cut-off those safety tabs since I'm the only one who moves the valve. Your valves seem to still have those tabs, so loosening the handle enough to turn the valve all the way to closed should do the trick.
 

mas985

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When I clean my filter, I open the pump lid first and then the filter air vent. This then drains the filter through the plumbing return saving some water. After it stops draining, I then open the bottom drain.
 
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