Pool Chemistry out of Limits

[rbposey]

Hello and thanks for all your help last year.

My water chemistry is as follow:

Chlorine 4
Ph 7.4


CYA 120
Alk 380
Hardness 100

The water is clear and perfect. Do I need to worry about the last 3 and get these into the recommended tolerences?

Rich

[CarlD]

Hello and thanks for all your help last year.

My water chemistry is as follow:

Chlorine 4
Ph 7.4


CYA 120
Alk 380
Hardness 100

The water is clear and perfect. Do I need to worry about the last 3 and get these into the recommended tolerences?

Rich

If your pool is vinyl, then the hardness is unimportant.

But with a CYA of 120, you need to maintain a chlorine level of (if I remember correctly) 8 or 10 to 15ppm. Otherwise you cannot count on it staying algae-free for long. You could drain half your water and replace it, which would drop CYA to 60--High, but easier to maintain--5 to 10ppm of Chlorine. But you better add bleach soon or risk trouble.

Alk is very, very high. You should lower it to prevent scaling.

Just because water looks clear doesn't mean it safe to swim in, or that it's going to stay that way. With a CYA of 120, a Chlorine level of 4 is going to have troubles killing the important stuff--bacteria. When algae grows all the Chlorine is consumed by it and there's none left to keep the water sanitary.

[rbposey]

Thank you for replying Carl. My liner is vinal.

I thought that you must keep the chlorine at or below 5ppm?

I had a terrible algae issue last year (pea soup). We went on vacation for a week and my filter shut off. I had to add so much chlorine I thought I would bleach my liner. I drained 1/3 of the water at the end of the season. So there is no way to reduce CYA other than draining?

Do I use standard pool chemicals to lower the alk?

Best regards!!!

[CarlD]

RB:
You need to do some reading. Go to our various forums and read the stickied threads we placed there. They will help you.

Also (ASAP) go to PoolSolutions.com and read ALL the tips there. They will give you a great headstart and aren't hard to follow.

The problem with most information we get from pool stores and pool companies is that it just doesn't make any sense. With your stabilizer (CYA) level of 120, you MUST keep your chlorine between 8 and 15 parts per million or you WILL get algae. With it that high you shock by raising chlorine to 25ppm. The maintenance and shock levels vary depending on the CYA level

That's why we have the "Best Guess Table" to show you.

To lower Alkalinity, there's only really one way.

Here's what I wrote on another thread:


There's really only one way, short of dilution with low T/A water to lower T/A and that's what's here. It's not always clear so here's how you do it:

1) Lower pH to 7.0-7.2. (Muriatic or dry acid are both fine) This lowers T/A somewhat.

2) Aerate your water. This raises pH WITHOUT raising T/A--and it's the ONLY WAY TO DO IT!

3) Lower your pH again to 7.0-7.2, bringing T/A down some more.

4) Aerate to raise pH again without raising T/A.

5) Repeat until T/A is in the desired range.

You "ratchet" your T/A down. T/A and pH are linked. pH goes up, T/A goes up. pH goes down, T/A goes down. ONLY BY AERATION can you break that cycle and do the raising of the pH without raising T/A, allowing you to lower it more the next cycle.

Here's the link:
http://www.poolforum.com/pf2/showthread.php?t=7561

That forum has a lot on lowering T/A.