Planning an AG pool

[Watermom]

That is some high alk and TA. Read the following about lowering alk and about using muriatic acid safely.

Lowering Alkalinity Step-by-Step

Using Muriatic Acid Safely

Also, trichlor is acidic and drives pH down. So, you'll need to be adding Borax to bring it up. But, then to drop the alk you'll need to add acid to drop the pH and alk and then aerate the pH up. It's gonna be a crazy cycle.

My opinion is that if it were my pool, I'd just add CYA outright and not use trichlor. Go ahead and let the pucks that you put in dissolve and then don't use more. That way, you can go ahead and start working to lower the alk.

Make sense?

[BethyM]

Thanks for the link! I had read another article about precipitating it out and it sounded like mucho effort! This makes total sense and seems so simple it's brilliant.

Questions:
1) When have you lowered the pH to a point that you can't swim? I guess a better question is, what are the water conditions under which you shouldn't let people in! I noticed in the article that it talked about 10 year old boys aerating. I personally think it's an excellent excuse for one of those fountains I've been eyeing up ;-)

2) How frequently are you adding acid and testing in step 5? I'm assuming we'd target 100ppm since clearly it's a fill water problem and may be a recurring issue of it creeping up over time. What is the range of pH where this is effective? If I maintain 7.2 and aerate, will I see a drop of TA over time?

I'm thinking that it may be a process best left to the end of the swim season if it means the kids can't use the pool but am super excited that it's such a straight forward effort. I was afraid I was doomed with my hard water forever! I'm still hoping the town puts in softening in the new water treatment plant -- we can hope!!

I'm off to add my CYA and put a dose of bleach in. How do you calculate the dose sizes? I've seen the online pool calculator but curious how others figure it.

[Watermom]

You can use the pool while you are working on lowering the alk. You won't want to drop your pH too low --- probably just to about 7.0 and then you start aerating it back up. It is fine to swim with pH at this level. A fountain is certainly one good way to aerate in addition to aiming the return jet upward to create a lot of bubbling and splashing on the water's surface.

You add acid again when you aerate your pH back up to 7.8 or so. Then, it is time for another dose of acid. Adding the acid drops the ph and the alk level. The aeration brings the pH back up without the alk rising. It is a ratcheting process and works great but it takes several cycles, especially when your alk is very high as yours is. It is not the aeration that drops the alk. it is the acid. The aeration brings the pH back up so that you can repeat the process.

To clarify for you, this does not affect the calcium hardness. It affects the total alkalinity which is not the same thing. One thing at a time. Once your alk is where you want it (and 100 is a good target) then you can see about lowering the calcium hardness. Ask about that later.

Regarding doses ------ the pool calculator is complicated. One that most people do better with is this one called the 'bleach calculator.' But, it has way more calcs than just one for bleach. If you click in the upper left hand corner, you'll find many more. After you have a look at it, let us know if you still need help figuring out doses and we'll be gad to help.

http://www.poolforum.com/zxq/BleachCalc262.exe

You're doing great!