New Pool Owner: Two questions

[PoolDoc]

OK. I just had to run some calculations.

1. Adjust your pH down to 6.8. See http://pool9.net/muriatic/

2. Use borax to bring it back up to 7.0 http://pool9.net/borax/ Start with 1/2 box doses.

3. Do NOT use baking soda ('Alkalinity Increaser', sodium hydrogen carbonate, "Balance Pak 100") or washing soda ('PH Up', sodium carbonate, "Balance Pak 200").

4. Continue to aerate your pool.


Once your carbonate alkalinity = 60 ppm, you should be able to soften submerged scale if you keep the pH around 7.0 - 7.2.

With respect to your heater corroding, pH values and salt levels are the 2 factors to watch. If your pH is 7.0 or above, it's fine. Do you have a salt system?

With respect to your heater scaling . . . it's almost certainly already happening. Lowering the pH and carbonate alkalinity will help soften and strip the scale.

[jayceedp]

Ben, Thanks so much for your reply.

The pool and spa are at the same level, divided by a low tile wall with a spillway. I try to keep the water level about an inch below the spillway and the flow over the wall is low, with no obvious bubbles. I can try to fine tune the mixing valves to reduce the flow. I haven't experimented with sending most of the return directly to the pool. There is a makeup line from the pool return to the spa, and that may be enough. That's probably what I'll do when I get the cover on.

If I understand correctly, you're saying that I need to get the TA down to 60 ppm using the aeration method. I have a blower on the spa, which I never use, and that should do the trick. How long do I wait between acid additions as I creep down to 6.8? Using the acid demand test in the K2006, I have an excellent idea of acid volumes for my pool to make small (.2 to .4) changes in Ph, but I'll follow your standard advice to use multiple doses for this big change. Does the borax act as a Ph buffer?

Thanks again.

John

[PoolDoc]

Not your TA, your CA (carbonate alkalinity). TA = CA + ~10% of borates + ~30% of cyanuric acid. So, maybe 80 ppm TA.

Both borates and CYA buffer pH, but not nearly as effectively at pool pH levels as carbonates.