BLowing sand out during backwash?

[CarlD]

The DE test is the easiest, fastest and cheapest test of your sand filter. Do yourself a favor and start there. 10# of DE should cost no more than $10, and you can use the rest to improve your sand's filtering capability as part of your normal routine. Most of us who have sand filters use the DE trick routinely--I'm still on the first 10# box after 4(?) years, at 1/3 cup each backwash.

As for checking the filter: Here my expertise is a little less than some other folks. But most top-mount sand filters have very simple internal plumbing that looks a little like an upside down umbrella with just the ribs, no cloth. The horizontal "ribs" are called laterals and usually fold up (like an umbrella) to the central vertical pipe for removal or installation. One of these laterals may well be cracked or have the holes in them blown out.

Here's the Catch-22:

You can't see them--they are buried under sand. So you'll have to dig out the sand and empty the tank of sand to be able to examine the laterals for damage. If you can save the sand, you can, as long as it is not gummed up. Or you can replace it, only using pool filter sand (sorry--pool store) and only using the amount your filter is rated for, which I believe is 350# (7 bags).

Also, whether the laterals are OK, or you have to replace damaged ones, they usually have a molded support in the bottom of the tank. Be sure they are seated correctly before you add more sand. I THINK you can get away with adding the sand dry, but your manual may tell you to mix it with water so it settles nicely. Again, I'll defer to other folks here.

But try Ben's DE test first, of a cup or 2 of DE in a slurry (a bucket of water with the DE in it floating around) into the skimmer and see if you get lots of blow-back into the pool. If it's all OK, flow should drop and pressure on the gauge should rise, then you'll need to back wash it out.

(Corrections and adjustments from "The Gang" are welcome!)

Carl

[greenwich3]

Thanks Carl

I will give this a shot as it seems simple. Thanks for your time giving this detailed answer.