Sand filter lid (top half) rises when filter is swtiched on

Pool pumps, pool filters and the plumbing of
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shaggy911
Pool Newbie
Pool Newbie
Posts: 2
Joined: Thu 17 Feb, 2011 01:49
My Pool: 20000 gal in ground pool; kidney shape;
sand filter; pump details unkn0wn

Sand filter lid (top half) rises when filter is swtiched on

Postby shaggy911 » Thu 17 Feb, 2011 02:25

i have an old (10 year old) sand filter. i think the brand of the filter is pac fab.
the sand in the filter was replaced a couple of months ago. Filter was running fine in fall. i backwashed it before winter.
Last week i noticed that when i switch it on the lid of the filter rises under pressure.
It is a drum shaped filter with a middle band that keeps the (shorter) top and (longer) bottom half of the filters together under pressure.

Why does the top part of the filter rise up? It was not doing this last fall - atleast i dont remember noticing it doing this.


shaggy911
Pool Newbie
Pool Newbie
Posts: 2
Joined: Thu 17 Feb, 2011 01:49
My Pool: 20000 gal in ground pool; kidney shape;
sand filter; pump details unkn0wn

Sand filter lid (top half) rises when filter is swtiched on

Postby shaggy911 » Fri 18 Feb, 2011 00:32

anyone? :(
poolacious

Sand filter lid (top half) rises when filter is swtiched on

Postby poolacious » Fri 18 Feb, 2011 01:27

This is quite normal Shaggy. You may notice more "swelling" after replacing the sand because the backpressure in the filter increases.

Most sand filters are made of fiberglass and the thinner the wall, the more this rise / fall is noticed at startup. As long as the return line is open, there are no problems associated with this.

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