DE in Pool, Air Leak?

[swing4terps]

Hi all. Season 7 opening our inherited pool, experiencing a new challenge. Our robot has been picking up DE with each clean (see pic for typical amount). I've done about 20-3 hour cleaning cycles since opening the pool a few weeks ago. DE pickup has been fairly consistent. Decided to do some testing and turned off the pump for ~18 hours and let the robot run. By last clean, there was very little DE in the filter.

Well I turned the pump back on this morning, and there was a ton of air in the system, and I was able to see dark (presumably DE filled) water entering the pool via the returns. I guess I had never noticed before because our pump is on a timer and starts at times I'm either not home or typically outside. I've manually started the pump closer to the previous shutoff time (~4 hrs) and observed some bubbles coming out of the returns, but not visible DE like this morning.

I'm assuming this means I have at minimum, an air leak. Suction side? Is this likely my only problem? The only thing different at startup this year was an attempt to fix the o-ring on my air relief valve. I will admit I don't know if I replaced correctly as the o-ring was completed broken, stuck in the valve. Could this be the cause? I have another valve on the way to either compare to or entirely replace my current one.

Any other things I should be checking? No other obvious plumbing leaks that I can see. Any suggestions on how to avoid what happened this morning until the new valve comes, other than running pump constantly or not at all?

Appreciate any guidance!

 

[Rancho Cost-a-Lotta]

The only thing different at startup this year was an attempt to fix the o-ring on my air relief valve. I will admit I don't know if I replaced correctly as the o-ring was completed broken, stuck in the valve. Could this be the cause?

This was my first thought. A leaky air relief valve will allow air into the system with the pump off, but will not always leak water under pressure. Try turning off the pump and listen closely for sounds of air being sucked into the plumbing.

 

[Casey]

Are your grids torn?

 

[swing4terps]

Are your grids torn?

Can't say for sure. I didn't notice any obvious tears when cleaning at the end of last season. Will admit, I didn't look at them at all before re-installing this season. As far as I can tell, the water coming out of the returns after pump startup appears to be clean, but hard to see if smaller particles, e.g. DE isn't coming out.

I think I might leave this as one of last things to check. Prospect of opening the filter at this point is not exciting!

 

[swing4terps]

This was my first thought. A leaky air relief valve will allow air into the system with the pump off, but will not always leak water under pressure. Try turning off the pump and listen closely for sounds of air being sucked into the plumbing.

I believe this to be at least one problem. I can hear air being sucked in at the valve with the pump off.

I tried to remove the adjuster on the valve to inspect and of course the air pushed a bunch of DE into the pool I had relatively clean. I have a new valve coming Thurs. I've put the pump on Recirculate for now.

Questions:
1) Is the leaky valve enough to cause these issues? (DE to return lines) Or might I have another problem like failing grids?
2) When it comes time to repair or replace the valve, what's the best way to move back to filter without letting more DE in the pool?

 

[Rancho Cost-a-Lotta]

1) Is the leaky valve enough to cause these issues? (DE to return lines) Or might I have another problem like failing grids?

Most likely the air relief valve is your problem. You'll know more after you get it fixed. If it continues, check the grids and MPV.

2) When it comes time to repair or replace the valve, what's the best way to move back to filter without letting more DE in the pool?

I don't have a MPV, but wouldn't you just be able to isolate the filter for repair by keeping the valve in recirc? When I clean my filter, I always get a bit of DE returning to the pool. I have an attached spa. When servicing the filter, I set the valves to spa mode to isolate the DE into a smaller body of water. In Spa mode comment clears up in just a few minutes.