Crystal clear water but turns cloudy once swimmers get in

Hi all - first, my specifics:

- IG 11k gallons with SWG, medium pebble (Stonescapes)
- Hayward cartridge filter, Polaris 380
- filter schedule is from 5pm to 11pm each day

Here are my latest test results using a Taylor K-2005:

FC: >5 (still need to get a FAS-DPD test kit)
CC: 0
TC: >5
pH: 7.4
TA: 80
CH: 330
CYA: 50
Salt: 2800
Borates: 40

The water is crystal clear until as few as one person jumps in, after which the water turns cloudy. The water always returns to crystal clear after a full filter cycle (by the next morning). I guess it's possible that the swimmers are just "dirty", but is this enough to turn the water cloudy?

Is it possible that particulate matter that the cartridge filter doesn't get is settling to the bottom after the pump turns off, then gets kicked-up after the swimmers jump in?

Yup.
Do you brush it? See if that makes it cloudy too.

Hi ChuckD - I did try brushing the sides on bottom of the pool to see if I could reproduce the cloudiness - I kicked some sediment up, but it didn't get as cloudy as it does when we're in there swimming.

I was doing some Googling and noticed that Polaris sells an Ultra Fine Sand/Silt Bag for the 380. The filter bag that I used right now is the one that comes with the 380 which is called an "All-Purpose Zippered Bag". Does anyone think this will help in collecting the particles the cartridge isn't getting?

Or maybe I'm just not running my pump long enough?

Would using one of those clarifier products help?

I'd guess you're not getting sufficient filtration. Try splitting your pump time into a morning and evening session and increasing the total time by a couple of hours (maybe 6 AM to 10 AM and 6 PM to 10 PM). If you're not brushing regularly that will help too; brush while the pump is running so that whatever gets stirred up can get filtered out.

You should probably also be running the pump when people are swimming (if you're not already). This will help get rid of the nasties the swimmers introduce and take advantage of them stirring things up.

another trick:
Throw a handful of cotton balls or a chunk of sheet cotten in the catch-bag. It will act as a filter and pick up a lot of fine stuff that otherwise just goes through the mesh.

This is the one drawback to pressure-side cleaners: They don't pick up the fine stuff. A suction-side, or a PoolBuster with the silt bag, or robotics all can pick it up.

Filter socks may help. I use ladies hose or knee highs. I cut the legs off about the knee on hose. I use my old clean ones. btw, I am a female. I also use one of these socks inside the polaris bag. I put the foot part of the hose in the bag, and overlap the connector part with the edge of the cut off hose or knee high. I have the fine silt bag for the polaris and this works well with it. Sometimes the hose slips off, but then it works kind of like the cotton balls that Carl mentioned. I hope this helps.