DE Filter plugs off in 3 hrs - why

[stromer]

I just put my de filter in service after sitting idle for 6 months during the winter. I cleaned the old de off the filter and put the normal amount of de on the grid. It plugged off in 3 days (the pressure went from 4 psi to 25 psi). The water was slightly green but the procedures I used were the same as in the past where the filter ran for several months before plugging. Thus something seemed to have changed. I found out that the filter probably had calcium hardness buildup in the filter cloth since it had never been cleaned of this since I bought it 3 years ago. I then acid washed the filter with muratic acid which was ok with the filter mfg - Hayward. This was meant to dissolve the minerals from the clogged pores with the acid. I then washed the filter with water. I thus thought the filter was cleaned of minerals that might have clogged the filter.

I then coated the filter leaves with the prescribed amount of de. The filter then plugged off in its first cycle - 3 hours with only slightly green water. Nothing different from previous operation where it ran for several months.

Can anyone give a possible reason for this rapid plugging.
I have done nothing different from past operation - nothing has changed.
However, something has changed, and I cannot dertermine what it might be. Thanks for any advice on this,
Rick

[JohnT]

Can anyone give a possible reason for this rapid plugging.

You gave the reason yourself: The water is slightly green. The filter is catching the algae and clogging. You've done what you should have in cleaning the filter, and you'll have to get the algae out of the pool. You need to shock to kill the algae, and then stay at that level. Once the algae is dead, it won't keep reproducing and the filter will begin to catch up. Vacuuming to waste will speed you along because you will remove particles without clogging the filter.