Suddenly the pool water has turned Milky

[CMPoolGuy]

My pool is generally trouble free (more than I can say for the SWG ) with only a constant drift towards alkalinity to worry about. I dosed it with cyanuric acid last week to maintain the chlorine level and it all dissolved normally but yesterday the water took on a noticeably milky appearance. You can see the bottom of the pool OK, but it's definitely not clear as it should be. The Chlorine is 1.8 mg/l and the pH 7.8 which is normal for me. I don't routinely measure any other chemicals.

Any idea what's happening and what I can do to stop it?

 

[wireform]

I can't see how 1.8 mg/l chlorine is enough. I think that's like having 1.8 ppm FC. You don't have enough chlorine to sanitize the water .

 

[CMPoolGuy]

I think I may have added too much CYA so I've drained about 15k litres and am refilling now. Will run the SWG at maximum for a day or two and see what happens.

 

[Msch99]

An expert will probably chime in but generally a SWG will not boost low CL quick enough. Good for maintaining but not a quick response. I would add liquid chlorine to get to needed cya/chlorine level. See pool school cya/chlorine chart

 

[Casey]

You should never use your SWG to boost chlorine levels. You need to provide a full set of test results using a recommended test kit. We can not help you until we can see what your numbers look like.

 

[CMPoolGuy]

I appreciate what you're saying, but sadly I don't have a decent test kit . The TF and Taylor kits recommended here are not available in Thailand (or at least I haven't found them yet) and so I've been making do and managing fairly well to date with just a Hanna pH meter and simple reagent set for Chlorine.

I seem to have made progress with the current problem by draining about 15k litres (30%) of the water from the pool and refilling it with mains water, adding 15 litres of 6% Sodium Hypochlorite bleach, correcting the pH to 7.6 and brushing and vacuuming the pool. I kept the filter running for 48 hours and backwashed and plan to do it again tomorrow. The chlorine level is off the charts on my test but the water has cleared by about 90% - maybe not crystal but very acceptable.

All very unscientific, but in these times of crisis about the best I could do . If anyone has a lead for good test kits in Thailand I'd be really pleased to hear from them.