Problem with circulation...

[Ripper70]

Hey All,

I'm having a weird issue with my pool circulation and it's making for an excessively long opening this season.

My kidney shaped pool has two skimmers and three returns. When I have the multiport set to recirculate, I have great pressure and circulation including suction through both skimmers. However, when the multiport is set to filtration, my circulation goes from perfectly fine to relatively weak over the course of about 20-30 minutes. Eventually, I'll have the skimmer farthest from the pump sucking at about 30% of normal and the skimmer nearest the pump with virtually no suction.

When I backwash or return the multiport to recirculate for a short while, the same thing happens. Good circulation for a few minutes then back to a trickle. As a result, I'm at the stage where the water is beginning to clear but is still milky and I'm needing to keep my FC at slam levels. Any suggestions for what is happening here or what I might check to remedy the situation would be greatly appreciated.

 

[mknauss]

Sounds like your filter is filtering out solids. Only other thing would be if the filter sand has been compromised by pool store potions such as floc or clarifier and is now plugged up.
You say you have milky pool water and are in the SLAM process. When did you start? What is your CYA and FC levels?

 

[Ripper70]

Actually, made the floc error last season and ended up replacing the sand entirely. Won't do that again.

Have been at SLAM levels for about 10 days but I don't really count the first 2 days as I use powdered shock to help elevate the CYA and get up to SLAM levels while taking the time to scoop out the sludge of leaves in the deep end. Went from swamp black to milky on about day seven.

CYA is 40 and FC was at 16 this morning. I added a gallon of 12.5% anyway to keep the FC level up. CC is 0.5. Ph is on the money at 7.5.

 

[mknauss]

Sounds like you are filtering. Be sure to let the filter pressure rise by 25% over clean pressure before you backwash.

 

[Ripper70]

I've been backwashing several times per day just because. I figure if the water is going from green to milky there must be enough reason to backwash. I'll do a 2 minute BW and then it takes about a 30 second rinse for the rinse water in the sight glass to go from clear to cloudy to clear again.

The BW action will solve the suction/circulation issues, but only temporarily.

 

[gonfishin]

Have you checked your impeller? We saw artificially low PSI on our pump and reduced circulation when there was some debris stuck on the impeller. For a while it would work, then it wouldn't.

 

[Ripper70]

Yes. The impeller is fine and turns freely. The strange issue is that there's less suction nearest the pump and circulation seems fine while the multiport valve is set to recirculate but goes from good to mediocre when set to filter. The skimmer nearest the pump slows to a trickle and as a result the water is still cloudy after about 5 days.