Sand in the bottom of my pool - can't fix

Problems relating to pH and total alkalinity.
Increase ph, increase TA. Reduce pH, reduce TA.
pH chemistry advice and techniques for the pool.
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Sand in the bottom of my pool - can't fix

Postby Me... » Tue 24 Mar, 2009 08:38

There are good sand filters and not so good sand filters, but that will be a construction issue. No matter what a 30" filter will have a max flow of about 100gpm. The "perfect" backwash rate will be about 75gpm. Now, how do you put in a pump that will do 100gpm against all the plumbing and fittings yet only do 75gpm on backwash. Simple, you don't. Well unless a person takes the time to install and adjust valves. The pump that does a 100gpm in filter will most likely try to do 125gpm or more on backwash.

A good closed-faced impellor 2hp pump will likely try to do about 130gpm on a properly plumbed pool. A mmm ahhh errrrr lesser quality open-faced 2hp pump might be lucky to do 90gpm. In any event it appears to me that a 2hp pump is too big for that filter and will cause it to have problems or at least not perform as well as it could.

If you pump water at too high a flow through a filter on backwash you can break the laterals, blow the media out of the filter, sandblast the inside of your tank, distribute the trapped debris throughout the filter bed and more.


Sand in the bottom of my pool

Postby Guest » Tue 24 Mar, 2009 11:15

i used 5 bags per manufacurers recommendation.

its been two days with no sand in the pool.

The filter may be blowing out extra sand or the new sand is still 'settling'. If there was some overfill, the excess can work its way into the pipes during backwash and blow into the pool later.

If the amount of sand is getting less then let's wait a while and keep tabs on it.

Sand in the bottom of my pool - can't fix

Postby opa » Thu 26 Mar, 2009 20:16


i guess what has me baffled is the the fact that the discharges are random in frequency and amount?


Re: Sand in the bottom of my pool - can't fix

Postby Bmguidry » Sun 07 May, 2017 07:54

I recently had problems with what I thought was sand but it turns out algae. Well I have they under control but since I have changed my sand and bought pool sand from department store turns out it's 20/40 sand when I need 20 grade and had sand going through filter with the stocking test. So I purchased sand from the pool supply and it said all grades on the bag, I questioned it and they assured me it was the right sand but now my problem is worse. It's seems to have gotten better but I'm exhausted changing sand I've torn the this filter down twice and inspected everything.. please help
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Re: Sand in the bottom of my pool - can't fix

Postby Denniswiseman » Sun 07 May, 2017 09:31

20 grade silica sand is what you need 40 is smaller and can find its way through the laterals

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