Probably pushing backwash valve to filter position too soon. Water draining down on tank as flowing though the ports and seeping into return line. Wait a bit and let the water in the tank drain out and then close valve.

Bump !!

My usual procedure is:

Shut Of the Pump
Set the MPV to Backwash
Backwash till the sight glass is clear.
Turn off the pump
Set to Rinse for 20-30 seconds
Repeat the above then shut off the pump and put it in Filter mode and recharge the filter.

Is this different than your procedure?

Scott

Scott are you saying that with all DE filters they should be
1. backwash till clear
2. rinse
3. backwash
4. rinse
5. filter mode

I have always done 1, 2, 5. I have never heard of the 5 steps. I am interested in knowing if I should be doing this differently!
Thank you in advance for your help~

I simply double up on backwashing persnickety filters. If it happens after the doubling, something is wrong in the filter and it should be opened, hosed out and more closely inspected.

If the MPV is balky, the spider gasket may need lube or replacing. If the handle has more than 3/4" of slack, the main spring may need replacing. Either of these can cause leaks in the MPV, with pump on or off or both. These internal leaks can sometimes let DE escape the tank.

I take it that when recharging, this doesn't occur. If it does, it's a pretty fair bet something is amiss in the tank. If it doesn't, start looking at the tank but also check the MPV.

Remember to close all valves and drain the tank. Removing the screws on the MPV without draining the tank will get you wet and DE in the MPV body, blurring things and requiring a rinse out.

Scott

thanx Scott..

I have the Jandy slide valve. not sure if thats the same as the MPV? Today I decided to take filter apart and clean grids thoroughly. I found excess DE buildup in between all the grids while grids still positioned upright before disassembly.. I'm probably not flushing out as much DE at or during prior backwashing. Also replaced worn O ring where manifold connects to return pipe. After starting up clean filter and adding 10 coffee cans of DE at skimmer, I noticed tiny white particles coming out returns for first hour or two after flter cleanout. White specs were more particle like than dusty or cloudy water with DE in it. Could this be specs of calcium depostes coming off grids. Filter grids and entire system is 4 years old this summer. Maybe its time to replace filter grids or soak in de-calcifying solution?

thanx again, Drew

If your hardness levels are consistently on the high side, degrease them with a TSP or Dishwasher Detergent soak first. Then a possible acid bath.

If the particles stop, then just the regular hosings and an occasional degreasing should do it.

Push/Pull and MPV are the two types of filter valves. They are very different. The incidents of shooting DE back into the pool is one of the whys I find the added head loss an MPV adds to be acceptable. The added versatility of the MPV is the other reason.

Scott