Ph 6.6 Alkalinity 50 HELP

[timmie]

I had thought of demolishing my pool, but city guidelines.....too much money

I tested my pool water 70,000 litres and these are the results
I did add about one box of borax and the numbers came up a little. How do I bring the combined chlorine down?? Do I just add a few bottles of Bleach??


free chlorine 5.3

total chlorine 6.1

Combined Chlorine 0.08
Ph 6.6
Hardness 190 ppm
Alkalinity 50
Cynaric acid 100

[aylad]

To bring the combined chlorine down, you need to shock the pool. With a CYA of 100, that means bringing the chlorine level up to 25 ppm. I'm assuming that you're using trichlor tabs for chlorination, which will drive your CYA up and your pH down. If so, I recommend that you stop using the tabs because you're going to fight a battle for the rest of the summer to keep your pool clear. Ideally your CYA should be around 40. Your pH needs to be at least 7.0 to prevent damage to your liner from acidic water. YOu can raise it by adding more Borax.


Janet

[CarlD]

Since your Total Alkalinity is so low (50), instead of Borax you can use Arm&Hammer WASHING Soda, in the yellow box. This will raise both your Alkalinity level AND your pH. I suggest dumping a whole box in to start, and plan on dumping in another within 24 hours--but test it in between.

[chem geek]

free chlorine 5.3
total chlorine 6.1
Combined Chlorine 0.08

The Combined Chlorine is a typo and would be 0.8 ppm given your free and total numbers. As was noted, you can shock the pool with chlorine to bring it down to 0.5 or below.

[timmie]

Hi,
I saw Washing soda next to the Borax in Super Store. Is there another name for it?? I usually dont use the pucks, but with my girls it seemed easier. All I have is Borax on hand. I will throw that in anyway.
If I shock the pool to 25, how does that make the combined chlorine go down?? How much should I use??

[chem geek]

It's Arm & Hammer Super Washing Soda and looks like this box.

[CarlD]

A&H Washing Soda is chemically identical to the pool stores' pH raisers, like pH Up!--but far cheaper. Both are Soda Ash--Sodium Carbonate.

Without getting TOO technical, Borax raises pH and, while it appears to raise Alkalinity, it's only the change in pH that shows Alkalinity higher. However, Washing Soda will raise BOTH pH and Alkalinity levels.

You COULD use Borax and regular A&H Baking Soda (Sodium BIcarbonate) to get the same effect but Washing Soda does both and is cheaper lb for lb.

Chem_Geek can explain it to you better, but FC breaks down the CC. It takes about 7ppm of FC to eliminate 1ppm of CC (I THINK that's the ratio--Richard, correct me if I'm wrong). So you need to shock sufficiently to get rid of the CC.

BTW, it's the CC that irritates eyes, nasal passages, skin, and has that distinctive "chlorine smell". You actually get rid of the smell in your water by adding more chlorine! My pool is usually around 6-10 ppm and you ONLY smell chlorine when you get out of the water --as it has been neutralizing the impurities on your skin and there's a local bit of CC there as a result--and you smell like chlorine!

[chem geek]

Chem_Geek can explain it to you better, but FC breaks down the CC. It takes about 7ppm of FC to eliminate 1ppm of CC (I THINK that's the ratio--Richard, correct me if I'm wrong). So you need to shock sufficiently to get rid of the CC.

The traditional industry rule is 10x, but technically that's really only for ammonia (which is measured in units 5x smaller than all types of chlorine including combined chlorine). For CC, the required amount is actually less than 1x, but you should shock with a higher FC to make it go faster. Shocking with chlorine at the shock level in Ben's Best Guess CYA chart will more quickly get rid of most CC. Keeping the pool uncovered and exposed to sunlight will also help.

[timmie]

Hi everyone, and thanks for all the advice.
here are my new numbers.
Free Chlorine 17.0 I shocked the pool
Total Clorine 0.0
Combined Chlorine -17.0
Ph 7/0
Hardness 170
Alkalinity 130
Cyanuric Acid 30

What should I add now to bring the numbers where they should be? I bought A&H soda wash today. I am not sure how much to add.
Another question is. How do I maintain my pool while I am away for a week?? Do I put alot of javex in it?? I am not sure what people do when they go away.
Thanks

[CarlD]

OK,
Those numbers change everything. Do NOT add either Washing Soda OR Borax! And don't add Baking Soda either.

You still need to raise your pH, but you can do it without increasing your Total Alk level (already at the upper limit) by aerating your pool. You can point the return at the surface, toss in a bunch of 12 year olds (in old suits), get a sprayer or fountain, and leave it UNCOVERED!

I have a $10 to $20 fountain that screws into the return instead of the eye that will aerate the water SO quickly that you can raise the pH rather rapidly that way.

This is now really the only acceptable way to raise your pH without causing problems.

It's a component of the process we recommend for lowering Total Alk...you lower pH to 7.0 (where you are) with acid, lowering Tot Alk with it, then raise pH with aeration--Tot Alk doesn't go up. Then you lower pH again with acid and that brings down Tot Alk some more, and you aerate to bring it up.

You are right at the point where aeration is the next step.

Then you'll be fine. BTW, your FC will come down from evaporation, sunlight, kids playing, etc.