Help with sand filter

[ntatro]

I have an above ground pool with the thick vinyl. It is 16' X 24' rectangular. 3.5 feet in the low end and 5 feet deep in the deep end. It is roughly 12000 gallons. It has a Hayward S-180T sand filter. Also I am on a well system.

The Problem:

After I back flush and rinse the filter it runs at about 14 PSI with really powerful return jet. After about 30 minutes the pressure goes up to about 20 or 21 PSI and the return jet is really weak. I have back flushed it about 4 times now and always the same result. It will run strong for 30 or 40 minutes then it goes weak again. When I put the system on recirculate it runs at a constant 12 PSI. I just replaced the gauge 2 days ago so I know it is working properly. I am not sure when the previous owner changed out the sand last. Any ideas of what could be causing the pressure to rise up so fast and the return pressure to drop so low? The water in the sight glass when back flushing doesn't look very dirty at all. I wouldn't think it could get that dirty that fast to cause this rise in pressure. Any help would be appreciated. Thanks.

 

[Texas Splash]

Your description sounds just like a filter that is being overwhelmed by algae. Algae isn't always green or visible, but often times begin with a large amount of organic matter that is almost transparent and simply clogs-up the filter. The only way for us to know is with proper test readings from one of the recommended test kits - TF-100 (link below) or Taylor K-2006C? Do you have one of those? If it is algae, no amount of filtration will resolve the problem. It becomes a chemical issue and must be resolved with a "SLAM" (link below).

 

[ntatro]

Your description sounds just like a filter that is being overwhelmed by algae. Algae isn't always green or visible, but often times begin with a large amount of organic matter that is almost transparent and simply clogs-up the filter. The only way for us to know is with proper test readings from one of the recommended test kits - TF-100 (link below) or Taylor K-2006C? Do you have one of those? If it is algae, no amount of filtration will resolve the problem. It becomes a chemical issue and must be resolved with a "SLAM" (link below).

I am in the process of doing a SLAM on it now since the water is pretty green and I assumed it had algae. I do not have a test kit yet. I was just wondering if something was possibly wrong with the filter or if it could really get dirty that fast. Thanks.

 

[Texas Splash]

It certainly can/will clog-up fast, especially if you can't test the FC at the high (specific) SLAM level required which most local testers don't support. So instead of filtering-out dead organic material, you end-up in that vicious cycle of clogging-up with live stuff. You might be killing some algae, but it's a guessing game. We also don't want you to over-shoot your FC too much based on your current CYA to ensure you don't bleach-out the liner. So be careful until you get either a TF-100 or Taylor K-2006C.

 

[zea3]

When you are dealing with that much algae the filter will fill up fast. Good news! Your filter works! Until the bulk of the dead algae is filtered out you will be backwashing fairly often.