Intermittently / cyclicly cloudy

[hartlenb]

Problem: My pool regularly goes milky cloudy. So much so that you can't see the bottom (only 5'). Other than it only occurs when the pump is running - it's completely random and it clears up. My pump runs twice a day for 4 hours a day. The milky-ness occurs somewhere in the middle of the cycle. Not every cycle but fairly often. It stays cloudy for awhile and eventually clears up. When the pump is off the water is crystal clear

Pool was just tested an everything is within spec according to the store
FC: 3
TC: 3
pH: 7.6
TA: 110
CH: not sure what this is
CYA: 60
Copper, Iron, Phosphates: all 0

My pool: 12,800 gal inground (Pool + spa)
Pool chemicals: salt
My pump & filter: cartridge filters, single stage
Other info: 

I've only saw one other similar post http://www.poolhelpforum.com/viewtopic.php?f=5&t=13047and there was no feedback on what was causing their issue. I don't think it's air bubbles as I don't see any bubbling at the surface.

If you have any ideas, let me know. The pool company is stumped.

[Denniswiseman]

Hi
You say your chemicals are salt, does that mean you have a SWCG
If so your CYA should be 70 to 80 as reccomended in Pool Levels and when the pump is running you get small chlorine gas bubbles in the pool causing the cloudiness
What level are you running your SWCG at as it's recomended that your SWCG should be double the size of your pool so that the SWCG doesn't work 100% causing a quicker failure
What are your salt levels as you need about 3000 for it to operate correctly
How are you testing? Store tests and strips are widely inaccurate

[hartlenb]

Hi. Thank you for helping.

My SWCG is Hayward T-CELL-15 running at 30% (the cell is rated for 40k gallon pools). The system itself says the salt level is 3000 ppm and the store said it was 2000. I'm very leery of the store measurement as they've messed up many times before. Do you propose a better way to test?

In terms of the CYA. I'll raise it but, if the cloudiness was the chlorine gas bubbles wouldn't it be cloudy for the entire time the pump was running? I only get intermittent cloudiness. In a 4 hour cycle it might be cloudy for 30 - 45 mins?

[Denniswiseman]

It seems that your cell is adequately sized and running quiet low
Try leaving the SWCG off and see if the bubbles occur then
I don't think you salt is a problem because you are producing chlorine and your cell normaly stops working when the salt is low
Taylor drop based salt test is one of the better ones. The K-1766. It's available from Tftestkits as well as several places
The Aquachek test strips are considered good.

[hartlenb]

So... I decided to check the filter cartridges myself. They weren't as clean as I was led to believe. I gave them a modest cleaning (didn't have time to do a great job) cranked the chlorine level high for 3 days and shocked it. It appears to have cleared things up. I'll go back and clean the filters properly and find a new service. Thanks for the help.