Normal for DE to be in pump strainer after shutdown?

[cruzmisl]

Hi All,
My pump is on a timer and at shutdown DE backs up into the pump strainer. I know this because the water inside the pump housing is milky white. Is this normal?

Thanks,
Joe

[waste]

Joe, the answer is NO! There is supposed to be some sort of 'bacckflow' prevention on the filter input to prevent the DE from going 'backwards' through the system.
Don't get me wrong, it's not a MAJOR problem, but it's not supposed to happen

[Poolsean]

Sounds like you may have a leak somewhere in your plumbing too. When the pump shuts down, the water should just remain in the pipes.
Think of it like a hose from one bucket to another. When the hose is filled with water, the water will flow from one bucket to another until they are the same level. The hose does not drain down. If you take this same hose and put a small hole in it, it will drain down.
Likewise, if your pipes have no leak, your pump basket, filter, heater, etc, will all remain "flooded" (filled with water). A leak will allow air to enter and allow the filter "stuff" to flow backwards. In this case, DE.

Are you seeing air in your pump before the pump starts back up?

To add to Waste's reply, the DE should coat your filter element and cling to it. If you have TOO much DE, the excess DE will not have anything to cling to, and can tend to drop off the filter element, and as Waste said, without the backflow preventitive check valve to stop it from heading back to the pump basket, will appear as the cloudy water.
Adding too much DE will reduce efficiency.

[cruzmisl]

Thanks for the responses. Upon further reflection, I think I know what is happening.

The original PB did not use any check valves in the system. I have a spa that is higher than my pool. When I shut the pump off the water tries to equalize and pushes backwards from my spa return through my pool returns and main drain/skimmer resulting in the DE in my pump. Sound possible? I bought a check valve prior to noticing this problem, just haven't installed it yet.

In the morning the pump basket is still full of water so I don't think I have a leak. Also when I installed the filter I literally weighed out the DE. I have heard of adding 80% of the suggested amount though.

Sound reasonable?

[waste]

Joe, the answer is YES - it's very reasonable Like Sean was talking about, overcharged filters will have reduced efficiency and the (without the backflow prevention) milky water in the pump. When you backwash or 'bump' the filter and open the drain valve to clean the used DE out, you only get ~ 80% out, so only put 80% back in to avoid the over charging. I'm assuming a 'bump- style' filter - if it's Hayward the 'check valve' is located in the inputpipe sometimes the weight falls off the rubber flap, other times the whole flap falls off - they can be seen and replaced by unscrewing the 'male'1/2 of the union. If you need more info on this- I'll be more than happy to help

[cruzmisl]

My filter is a Pentair FNS Plus-it doesn't have a "bump" option. I only ever cleaned it once and I took it apart and cleane dit out totally. I'm going to install the check valve tomorrow and see if that makes a difference. I'm not sure if the filter itself has a check valve. I have a multiport valve if that matters.

Thanks for the help