New Pool owner water chemistry

[sammm]

I've been reading the forums and trying to figure this out. I'm getting there, but still not sure and have much to learn. I tested my water myself ( I don't have a calcium or CYA test yet), and things seem OK to me. I took a water sample to my LPS and had them test. Here are their numbers:

FAC - 2.5
PH - 7.4
TA - 100
Calcium - 440
CYA - 100

I asked about the calcium and CYA (seem high) and he said the only way to lower them is to partially drain the pool. Are those high enough that I should worry and/or drain?

The pool is an IG concrete 17' x 32' rectangular play pool. 4' deep on the ends and 5' in the middle. It has an inline chlorinator and a DE filter. Water temp is currently around 70-72 degrees. Using a volume calculator I came up with ~18,000 gallons. Thanks in advance for any help!

[CarlD]

When you say you have an in-line chlorinator I'm assuming you have the kind you add Tri-Chlor pucks to. If, in fact, you mean you have a Salt Water Generator of chlorine, then what follows is NOT relevant to you.

He's right. Unbelievable that I'm saying that but it's true.

I would STRONGLY suggest you drain about half the water out of the pool and refill. Then turn off your inline-chlorinator and stop using chlorine pucks. Your CYA is excessively high and the pucks keep adding more and more CYA.

Drain half and CYA AND Calcium should be cut in half. CYA at 50 is a good number. Calcium at 220 is near the low end for a concrete pool (200-400) but OK.

You should now chlorinate with plain bleach or liquid chlorine (same thing, different package). Or make the break and replace the inline-chlorinator with a Salt-Water Generator for chlorine (see folks? I'm not against SWGs).

Using bleach you may see your pH start to rise. You may not (the pucks are VERY acid!) If so, just use muriatic acid to lower it.

But if you decide NOT to drain and refill, you will need to maintain your chlorine level between 10 and 15 ppm (I believe). That's hard to measure unless you have a FAS-DPD test kit for chlorine. Your calcium will still be high but it may come down as you do backwashing and replacing of water.

But if FAC is your chlorine level you are about to get in big trouble. You need to shock your pool NOW. I would add 4 gallons of regular bleach--5.25% ( just to get your chlorine to 12 or 13, at a minimum--which is your maintenance level. But I would seriously suggest you add 8 gallons of regular bleach to actually shock it.

IMHO

[waterbear]

He's right. Unbelievable that I'm saying that but it's true.


IMHO

Carl, It not the first time you've agreed with a pool store guy!

Sammm,
Carl is, as usual, right on the money. Listen to him!

[sammm]

Thanks for the replies. Carl, you are correct that my chlorinator uses the pucks. Not a SWG.

Just so I've got this straight, once I drain the pool I should stop using the pucks permanently and switch to bleach. Correct?

You also said if I decide not to drain and refill. What are the pros/cons (I'm guessing mostly cons) in that method?

Thanks very much for the help, I really appreciate it!

[CarlD]

If it were me, I'd drain half the water and refill. You can also drain 1/4 of the water and refill--your CYA should come to 80 then.

Aylad lives 'way down South and she finds she needs to run her CYA at 80. Otherwise the sunshine and other stuff eats her residual chlorine too fast. So by running 80ppm and her FC in the 8-10ppm range for normal swimming, she doesn't have to keep adding excessive chlorine.

OTOH, she has to test to a higher level, but that trade-off works for her. I'm in a cooler climate and the sun is less intense so I prefer to run CYA in the 30-50 range, no higher.

[sammm]

I should stop using the pucks permanently and switch to bleach.

way down South and she finds she needs to run her CYA at 80. Otherwise the sunshine and other stuff eats her residual chlorine too fast. So by running 80ppm and her FC in the 8-10ppm range for normal swimming, she doesn't have to keep adding excessive chlorine.

I'm starting to understand now. But back to one of my questions (shown above). You suggest to ditch the pucks totally (after I drain) and switch to bleach, right? Thanks again Carl!