DE getting back in pool

[sw20rules]

Hi all, I've been trying to tackle this problem ever since moving into my home. Basically everyday in the morning I would see small clusters of DE at the bottom of the spa and the a lesser extend, the pool. I would vacuum it away and it would come back the next morning. I read a bit about the possible causes such as ripped filter, etc. and proceeded to change out the filter grid set and manifold. It did not help much and I ended up hiring a professional to look into the problem, he was unable to remedy the problem as well so I am hoping the collective knowledge of this forum will guide me in the right direction. Here are the parts that have been replaced /added:

New filter grid set
New filter manifold
New O-rings on backwash valve (push pull type)
New O-ring on pipe that attaches to the grid assembly inside the Hayward filter
New O-ring between the two halves of the Hayward filter (the large one)
New O-ring on the pool pump basket window
Pool professional added check valve to help stop DE flowing back from skimmer

One thing I want to mention is when the pump is running, you cannot visibly see DE coming out of the return jets. However, if I go into backwash mode, run it for 10 seconds or so, then turn it back into filter mode, you can visually see DE coming out of the return jets for about a minute or so, and the spa will immediately become very cloudy. The pool professional double checked the grid is fine and mentioned if there is a rip the DE leak will be constant. Any help is greatly appreciated.

 

[poobears]

Are you waiting after you backwash or going straight to filter? I think if you don't let everything settle before switching back to filter it can flush out some. I've heard of it happening with sand filters, not sure if DE is the same. Hopefully someone more knowledgeable than me will pop in soon.

 

[sw20rules]

I typically wait a minute or so for the water in the pipes to settle before switching modes.

 

[Richard320]

You might have a suction side air leak and a big bubble in the tank. When the pump is on, it compresses. When the pump shuts off, it expands and pushes backwards through the system, which can push small amounts of DE out.

Open the bleed valve after the pump has been on for at least a few minutes and see if any air escapes.

 

[sw20rules]

Thanks I will check that. I do believe some air do get in the system, especially when I use the pool cleaner. That would explain the small amount of DE that might go back from the drain. But what about the DE that comes out from the return jet? The amount is significant enough to cloud up the spa within a minute when turned to filter mode after backwash? Doesn't that mean some how DE is getting pass the filter?

 

[Richard320]

Thanks I will check that. I do believe some air do get in the system, especially when I use the pool cleaner. That would explain the small amount of DE that might go back from the drain. But what about the DE that comes out from the return jet? The amount is significant enough to cloud up the spa within a minute when turned to filter mode after backwash? Doesn't that mean some how DE is getting pass the filter?

That is more likely residual in the plumbing indicating you didn't backwash long enough.

 

[barefooting]

Not sure if this will help you, but I had a similar problem.

I had to replace the flapper on the check value from my solar system and also the spring and spider gasket in the multi-port valve. When the solar drained, it pushed some DE back towards the pump (due to the bad check value). I could see DE in the pump basket. I don't believe I had a good seal in the multi-port value and some DE made it back to the pool when the pump was turned back on. I also replaced the bleed valve on the top of the filter, just in case that was leaking and letting air in when the pump was off. Wasn't sure if that was bad, but I thought if it was leaking, it would allow some DE to flow back towards the pump.

I think anything that could allow water to flow back towards the pump will loosen some DE, and if the seal in the multi-port isn't good, it could mix back into the return lines when the pump is turned on. That is of course, if you have a multi-port valve.

 

[rterickson]

If your multiport valve has a 'rinse' setting, try rinsing for one minute after backwash before going to 'filter'.

 

[sw20rules]

Thanks for the suggestions guys. The pump basket does get cloudy if I leave the pump off overnight. I have one of those push/pull valves and the o-rings have been change on them. I confirm there is nothing draining from the waste pipe so air should not be getting in there. A new check valve was added by the pool technician specifically to eliminate the possibility of air leaks in the pipes.

 

[ontherocs]

Hello! We think we may have a similar problem. Did yours ever get resolved?