Which to fix first? PH level or Alkalinity

by Dan
(Ohio)

Chlorine residual - 0ppm

PH - 8.2+
Alkalinity - 50ppm
Hardness - N/A
Cyanuric Acid - N/A

Cartridge filter system with 1hp motor on pump.
24', 52" deep above ground round pool.

So I'm trying to help my father-in-law get his pool going in his recently purchased house and the pool balance is off. He put in some copper algacide that caused foaming in the pool.

After lots of skimming today it's better, but not perfect. He also added a bag of shock and swim.(1lb)We have no chlorine residual however the pool has a fairly strong chlorine bleach smell.

As you see above the alkalinity is low and the PH is to high so which do I fix first?

Do I lower the PH first by adding Acid and then worry about Alkalinity or add Baking Soda first to raise Alkalinity then worry about PH?




Thanks for the question Dan

There are a few things going on here. I'll do one at a time. First is the CYA. Does N/A mean you're not getting a reading or you're using strips and can't get a reading? If it's 0ppm you need to get some CYA in the pool immediately.

With a pH of 8.2+ and no chlorine you're opening yourself up to algae. You can either use straight up powdered CYA plus liquid chlorine or Dichlor chlorine which is an already stabilized form of chlorine. Both Dichlor and straight CYA is 1 lb. per 10,000 gallons to increase the CYA 10ppm. The range for CYA is 30 - 50ppm.

Next is the pH and TA. The pH is too high, which you already know. The range is 7.4 - 7.8. The TA is slightly low but nothing to worry about right now. The range is 80 - 120ppm.

The first thing that I would do is to increase the CYA to 30ppm. Do this in stages, not all at once. You don't want to over-shoot the 30ppm mark.

I may be jumping to conclusions. If the CYA is high, above 80ppm, you'll need to do a partial drain and refill. There's no other cost effective way to reduce the CYA, I'm just assuming it's low.

Then there's the Shock N Swim. This is nothing more than regular calcium hypochlorite, just marked up. Don't use this for a couple of reasons. First I'll assume Ohio has hard water. You're adding hardness (calcium) to the pool which you don't want to do. 2nd, cal hypo has a pH of 12. When you shock the pool with cal hypo you're jamming the pH up which you also don't want to do.

Here's a video I made about that:

https://www.youtube.com/watch?v=JkeEYAsEzKI

Use liquid chlorine. It's 1 gallon to increase the CL 10 - 12ppm per 10,000 gallons.

Here's another video about shocking your pool with cal hypo.

https://www.youtube.com/watch?v=vVgchMIa_qM

Next is you'll want to add acid to bring the pH down to the proper range. It's 0.8 qrts (about 20 oz.) of acid to lower the pH 0.2 per 10,000 gallons. You want to decrease it from 8.4 to 7.4 so you'd use approx. 100 oz. Don't do this all at once. Maybe do 40 - 50 oz., allow to FILTER for 10 hours, retest, and make another adjustment.

Never use a copper algaecide for the reason you gave. Foaming is common with this kind. Only use a PolyQuat 60. It's a bit more expensive but worth it.

To sum it up:

1. Add the CYA and sweep

2. 2 hours later add the acid around the perimeter of the pool and sweep

3. 2 hours later shock the pool with liquid chlorine

4. Allow to FILTER for 10 hours then retest the CYA, pH, TA, CL, and make another adjustment if needed. Follow the same order as above.

The acid may slightly hit the TA but nothing to worry about. You increase that with baking soda. If it does get lower simply turn the system OFF and add the bicarb in one spot. Allow to sit for 3 - 4 hours, then system on to FILTER for 10 hours, retest and make another adjustment if needed. It's 1 lb. of bicarb to raise the TA 10ppm per 10,000 gallons. You can do this last.

I hope this has answered your question to your satisfaction.

To post a reply, or if you have a similar question, you can see your post on the Q&A page in the "Alkalinity" category.

Check back to this post for updates or answers.

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Have a great Summer.

Robert

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