Dirt returns to the pool after backwashing

Hi,
After I vaccuum the pool, backwash and turn the pump back on for regular circulation, dirt I just vaccuumed shoots back into the pool from the returns.

When I backwash, I make sure to do it long enough to both run clear and to give it an extra 30 seconds for 'good measure'. The result is the same regardless how long I backwash for - once I turn the filter back on it shoots out dirt for about 15 seconds. It's a sand filter.

Thanks!

After you backwash, you should put it on the "rinse" setting for 15-30 seconds before putting it back on filter. That should take care of the problem.

Thanks Watermom.
It's an old sandfilter and I don't have a 'rinse' setting.

Have you checked the spider gasket in the multiport backwash valve, or do you have a push/pull valve? If you have a push/pull valve (two positions, up and down) then the plunger might be worn and not seating well.

Are you backwashing long enough? The one time I had that happen to me was when I rushed and the backwash had not cleared out the junk yet. I wait until the small glass bottle at the top of the pump has clear water going through it. Not sure if that is possible with your set-up, just a situation with mine.

Do you have a "Waste" setting, so you can vacuum to waste? If so, the "Waste" setting is the same as the "Rinse" setting.

Thanks guys,

CarlD: I only have a push/pull valve so it's either backwash or standard.

Spensar: Yes, I've backwashed several minutes past the point of when the water runs clear to be sure.

Waterbear: It's a push/pull valve. I took the 'plunger' out today and examined it. It's old but didn't appear to have anything wrong with it. I lubed the o-rings up again and set it back in. After vaccuuming and backwashing tonight I held just a little hope that the reseating the valve would make a difference but no luck. It's like a punch in the stomach to see the dirt spew back out after vaccuuming in 110 degrees (AZ) :(

Is there a telltale sign that I could look for if the valve isn't seated properly?

Thanks!!

bumping this thread back up....