Test results - bluish cloudy pool

I have been using Ben's kit all summer and have been quite happy. It is so great to know what the CC is! I'm sure I've saved a ton on chlorine.

Pool has been running well all summer, but in the last two days it has started a slightly bluish cloudiness - not greenish like algae. I know I have high calcium and high alk, wondering if this is finally having some effect.

I do have scale deposits on the pool walls and have had all summer.

Suggestions please:-)

26,500 gal IG vinyl lined pool
FC 4.5
CC 0
TC 4.5
ph 7.8
alk 160
cal 210 (or more - not sure how "blue" the sample is to turn. I stopped when it turned just past reddish hue into a bluish hue)
cya 30
water Temp 76 (we've had a cool spell with freezing at night. Life in the mountains!)

I haven't messed with alk because my ph doesn't tend to creep up. This is the highest it has been all summer.

My plan is
1) do Ben's alk reduction process using muriatic acid, to see if pulling the alk down closer to 110 may help, then keep ph at the lower end of 7.4.
2) keep the chlorine level up at 5.

Not sure if I need to mess with calcium due to scaling.

Thanks for any help!

Well the calcuim level is fine - if you have a vinyl pool anything under 500 is fine. If a concrete plaster pool it is receommended to be between 200-400.

Yes your ALK is a little high, but I don't think it is high enough to be causing cloudiness.

Does the pool hold chlorine overnight? If it doesn't - the cloudy is caused by some organics in the pool. Try shocking to see if that clears it up.

That's really puzzling that your pool water would produce scale. Have you confirmed that's what it is? Does acid foam up when you apply it to the scale?

Nothing in your test results (thanks for posting those) would indicate anything far enough out of whack to give you any problems. Has your pH slipped up over 8 this Summer?.....not according to your description...hmmm.

That's really a puzzling issue and I hope you discover the cause so we can all learn from it. Sorry I have no suggestions.

Thanks for the quick responses.

I am certain my ph hasn't gone past 7.8, unless my test kit is bad (grin). I'm guessing it is scaling on the walls. I haven't tried washing it off at all because it is not a priority to worry about it, so I don't know if acid would foam. Basically, if I rub the side of the pool above the water level with my finger, it takes a minute before the wall comes clean. I'm assuming it's mineral deposits because that's just the kind of water we have.

Regarding holding chlorine overnight, I haven't noticed any significant drop, usually just 1 or 1.5 loss each day with just our family using it. My understanding was that if there is organic matter in the pool it would be "eaten" by the FC, which would produce CC, so if my CC reading is 0, its clean. (This is the "I'm not a chemist" understanding.) Am I a bit off in my thinking on this? Should I give it a shock just in case, or is that a waste of bleach with 0 CC?

If the alk truly isn't a problem, I may just ignore it, except to pull down the ph again, since I have mur. acid on hand. Wouldn't mind NOT storing if for the winter.

I don't think that's scale....it would not come off with your fingers and I don't believe it would normally precip out onto the vinyl. Shocking the pool is a painless, inexpensive possible fix.

You really use little if any extra chlorine....it simply stays in the pool at higher concentrations for a while. I'd bring the Cl up to a solid 15 one evening and test again the next morning. If you have a large drop, you'll have found the issue. Once or twice will probably return the water to the crystal condition you had.

Let us know what you find.