How to tell if filter needs replacing

[dojoman59]

I have just slammed the other pool I care for, followed the instructions on here and the pool passed the 3 criteria for slamming. Have got the pool water chemicals all settled,
FC 6.4
CC O
TA 82
PH 7.4
CYA 48

However the water appears to have lost its sparkle and I am not sure why, as stated above the results are all fine, the only thing I can think of is that the filter needs replacing. I did a deep clean of it before I refilled the pool but the sand has never been changed in 7 years, and the pool is in a very dusty environment. Is there any sort of test to confirm whether this is the case?

 

[needsajet]

About the only test is watching that the changes in pressure are normal and what you've experienced in the past. It can take quite a while for a sand filter to fully clear the water. Sand almost never needs to be changed and you've done the deep clean which is great.

Running the pump more hours than usual can help clear the pool. Making sure you let the pressure rise and not clean too often can help (don't backwash until dirty pressure is 25% above clean pressure).

You can try adding diatomaceous earth (method linked below) to help filter out smaller particles than the sand filter can do on its own.
Pool School - Add DE to a Sand Filter

If you try this procedure, be sure to buy DE for pool filters, not the gardening type. Add the DE on a day when you can keep a close watch on filter pressure after adding the DE and for the rest of the day. Also check it in the morning of the day after. The next time you backwash, the DE will be washed out, and you replace it by following the procedure again.

 

[domct203]

I have just slammed my pool, followed the instructions on here and the pool passed the 3 criteria for slamming. Have got the pool water chemicals all settled,
FC 6.4
CC O
TA 82
PH 7.4
CYA 48

However the water appears to have lost its sparkle and I am not sure why, as stated above the results are all fine, the only thing I can think of is that the filter needs replacing. I did a deep clean of it before I refilled the pool but the sand has never been changed in 7 years, and the pool is in a very dusty environment. Is there any sort of test to confirm whether this is the case?

What test kit are you using that gives a TA result of 82ppm and a CYA result of 48ppm?

Is the FC a FAS/DPD test?

Dom

EDIT: I now see the Pool Exact EZ photometer in your signature.

 

[dojoman59]

Thanks for the replies, unfortunately the pool that is giving me trouble is not mine, it is the bigger 1 of the 2 in my signature so I am not at the property all the time. I am caring for both pools in an identical manner and mine is absolutely brilliant. The only difference being that I changed my filter medium to glass in Nov 2015. I have only been caring for this pool for a few months so I don`t really have a great idea of the normal pressure on the filter. When I took over the pool it was in a horrible state and the pool cleaner was not doing his job properly. I ended up ditching all the water as the CYA was 200 ppm. Now it is in a lot better shape, the water is clear but not sparkling although it was when I was slamming it. I think I am going to recommend that they get the filter medium changed.

 

[treatmentnerd]

By chance, is the pressure high? I had a problem with my oversized constant speed pump putting too much pressure on my cartridge filter and basically blowing stuff through. I had a pressure of 28 psi on a clean filter though, so my situation was fairly extreme. If your pool is similarly out-of-range (ie, over 20 after a backwash) your problem may have more to do with the pump than the filter.

 

[dojoman59]

Thanks for the reply, the pressure is about 14 psi and is quite constant.