Filtration problems / pump size

[thedubb]

Hello, needing information about pump size (HP). I'm a new pool owner and purchased a pump and filter system used from a friend and I'm concerned the pump is too large. My sand filter has a filtration flow rate of 34 GPM. Not sure if that is the MAX or recommended.

Pool Specs:
15 x 30 Oval approximately 10500 gallons
Pump - Hayward 1.5HP
Filter - Hayward Pro Series S180T 34gpm
1.5” tubing.

I used this system last summer with poor success. I had cloudy water all year. You could see particles in the water all the time. Chemicals were good. I took many samples to the store for testing. When I went to remove the cover the other day it failed and a lot of debris went in the pool. I have very dirty water so I got it tested and started the shocking process.
After a couple of days of no improvement (water turned bluish green but not clearing) I disassembled the filter and found the assembly was cracked so I replaced it and added 150lbs new sand. I also replaced the control valve assembly because it stopped backwashing. When I first turned on the filter after the repairs, it had much more output pressure. However, in less than an hour, it died down to just a trickle. I backwashed, rinsed and it had massive output again. Filter and strainers are clean, no blocks in lines.
Is the algae clogging the sand that quickly? Or is the pump to strong and messing up the filter?
I know from researching that a 1.5hp pump can move approximately 80 gpm. My lines are 1.5” which should reduce that down to approximately 44 gpm but is that still too high for the filter?

[PoolDoc]

1. Your pump IS too large.
2. A properly operating sand filter may be stopped up by heavy algae quickly. That is a GOOD thing: it is filtering out the stuff you want out.
3. You'll probably get longer filter runs if you KILL the algae with repeated late evening applications of bleach (2 - 3 gallons of 6% bleach each evening, till all the green is gone)
4. Depending on which model Hayward pump you have, it may be possible to replace the seal, impeller, and diffuser with parts for a 1HP or even 0.75HP pump. This will reduce flow AND electrical consumption.

[thedubb]

Thanks. I just didn't think it should get stopped up that quickly. If I can't retrofit the pump I'll probably buy a new one. Most sites don't list any GPM rating for their pumps, very frustrating. I'm with you and think a 3/4 hp will be more than sufficient. The 1.5 I have is probably why the filter assembly and valve had to be replaced. Are there any health concerns with using bleach in place of shock?

[thedubb]

Sorry, one more thing. After adding the bleach or shock should I leave the pump running or shut it down for the night? I've been running it 24/7 to try and get this cleared up.

[PoolDoc]

It's common for AG kit manufacturers to oversize pumps, because pool purchasers naively assume that more HP = better performance. And, it's cheaped to increase pump HP than it is to increase filter size.

[mas985]

Do you have a model # for your pump? Not all 1.5 HP AG pumps are that "large" and most are smaller than 3/4 HP IG pumps.

[CarlD]

Sorry, one more thing. After adding the bleach or shock should I leave the pump running or shut it down for the night? I've been running it 24/7 to try and get this cleared up.

Keep the pump and filter running 24/7 till it's back to normal.