Hey TFP community,
Quick summary: I don't think my filter is actually cleaning the water at all - the pressure doesn't change from sediment build up, the backwash looks clear, I added a few scoops of DE to the skimmer and my robovac just pulled it off the bottom of the pool. Is this a failure mode for older sand filters?
Longer story:
I bought a house last year and it came with a huge old pool - 45k+ gallons, 10ft deep end, etc (our first pool). The only equipment it had when we purchased it was an old Sta-Rite 300lb sand filter and a 1.5hp single speed pump. All of the underground piping except the skimmer line is broken, so the return was formerly a piece of 1.25" poly tubing across the deck. I added a heat pump this spring (all plumbed in with 2" PVC) and ran new PVC on the other side of a parallel fence to add two 1.5" PVC return pipes. A temporary solution until we undertake a pool remodel. The skimmer line isn't 100% sealed so it was sucking air and causing some cavitation, so adjacent to my new return, I added another supply line 10' down and added a jandy three way valve so my pump isn't so supply restricted. All of that worked well, the PSI in my filter increased by ~8 to 30psi and things were looking okay.
We had a pool guy who was terrible and just shocked the pool every week. I got a test kit (and bought Pool Math) and there was literally no detectable stabilizer in the pool at the beginning of June. Imbued with confidence from TFP, we let the pool guy go and I took over.
Since then it's been a bit rocky -- we only have the robovac (a Polaris 9350 Sport) but it stopped working about 3 weeks ago. It turned out the cable had a short in it, so I rewired the thing and got it working again, but the pool didn't get vacuumed for probably two weeks. In that time, even with FC near 4 (with a CYA of 30), the pool started to get cloudy. I should have started the SLAM then, but thought I'd try adding a little DE to my filter to see if it wasn't just cloudy from pollen or other suspended stuff that was visible in the pool. I added the recommended amount of DE and the pool became *substantially more cloudy* almost immediately. My robovac returned several times with a bunch of DE in it's hamper.
From then it never really got better, it stayed cloudy for a few days, and then started turning bright green. I'm on day 2 of SLAMing it now, but even with that DE, with all of the grossness in the pool, my filter just runs clean. When I backwash from the filter, I can no longer see any color change in the water, in stark contrast to earlier this year before I upgraded the supply. The filter is still far below nameplate rating in both flow GPM and PSI, but it just "seems" like the filter is no longer working.
Is that a possibility? I'm happy to do a sand change since the prior owner said it had been 8 or 9 years, but is there anything else that would be causing this? We don't get much sand in the pool, so I don't think it's a broken lateral, but how did all of that DE make it through the sand and end up on the bottom of my pool? And why is my backwash free of dirt? Could the higher pressure / water flow effected it in some way i can't conceive?
At a complete loss.
In case it's relevant: FC 12, CYA 30, pH: 7.3, TA: 100, CH: 200, Temp: 83º and I'm in West Michigan.
Quick summary: I don't think my filter is actually cleaning the water at all - the pressure doesn't change from sediment build up, the backwash looks clear, I added a few scoops of DE to the skimmer and my robovac just pulled it off the bottom of the pool. Is this a failure mode for older sand filters?
Longer story:
I bought a house last year and it came with a huge old pool - 45k+ gallons, 10ft deep end, etc (our first pool). The only equipment it had when we purchased it was an old Sta-Rite 300lb sand filter and a 1.5hp single speed pump. All of the underground piping except the skimmer line is broken, so the return was formerly a piece of 1.25" poly tubing across the deck. I added a heat pump this spring (all plumbed in with 2" PVC) and ran new PVC on the other side of a parallel fence to add two 1.5" PVC return pipes. A temporary solution until we undertake a pool remodel. The skimmer line isn't 100% sealed so it was sucking air and causing some cavitation, so adjacent to my new return, I added another supply line 10' down and added a jandy three way valve so my pump isn't so supply restricted. All of that worked well, the PSI in my filter increased by ~8 to 30psi and things were looking okay.
We had a pool guy who was terrible and just shocked the pool every week. I got a test kit (and bought Pool Math) and there was literally no detectable stabilizer in the pool at the beginning of June. Imbued with confidence from TFP, we let the pool guy go and I took over.
Since then it's been a bit rocky -- we only have the robovac (a Polaris 9350 Sport) but it stopped working about 3 weeks ago. It turned out the cable had a short in it, so I rewired the thing and got it working again, but the pool didn't get vacuumed for probably two weeks. In that time, even with FC near 4 (with a CYA of 30), the pool started to get cloudy. I should have started the SLAM then, but thought I'd try adding a little DE to my filter to see if it wasn't just cloudy from pollen or other suspended stuff that was visible in the pool. I added the recommended amount of DE and the pool became *substantially more cloudy* almost immediately. My robovac returned several times with a bunch of DE in it's hamper.
From then it never really got better, it stayed cloudy for a few days, and then started turning bright green. I'm on day 2 of SLAMing it now, but even with that DE, with all of the grossness in the pool, my filter just runs clean. When I backwash from the filter, I can no longer see any color change in the water, in stark contrast to earlier this year before I upgraded the supply. The filter is still far below nameplate rating in both flow GPM and PSI, but it just "seems" like the filter is no longer working.
Is that a possibility? I'm happy to do a sand change since the prior owner said it had been 8 or 9 years, but is there anything else that would be causing this? We don't get much sand in the pool, so I don't think it's a broken lateral, but how did all of that DE make it through the sand and end up on the bottom of my pool? And why is my backwash free of dirt? Could the higher pressure / water flow effected it in some way i can't conceive?
At a complete loss.
In case it's relevant: FC 12, CYA 30, pH: 7.3, TA: 100, CH: 200, Temp: 83º and I'm in West Michigan.
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