sand filter problem.
 

I have a nicely sized sandfilter, 2 inch tubing, 1.5 inch hp motor and
a 17000 gallon inground pool.
I installed the filter last year myself (replaced a cartridge filter)
and filled the filter with the zeobrite/zeosand (can't remember
exactly which) sand. I used half the required amount for normal sand ,
as directed by the instructions for zeo.
The filter is a hayward filter, the switch and piping connect on top.

Here is the problem;
Every time the pump switches on for its 8 hour run, I see a puff of
cloudy water coming out of the returns into the pool. It is only
briefly. It seems to disappear almost right away but the water is a
bit cloudy after this until the pump has run for a while.

It started doing this after I changed the filter so that makes me
think it's something with the filter.

any clue why ? The new filter was installed months ago and has been
backwashed several times so I would think any impurities in the sand
are now gone.

and yes, I do use Rinse after backwashing.

thanks

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