Lowering Alk -- fountain or ripple

[dhale1]

Ok, my PH has been creeping downward and is now low enough that I can try to lower the alk. Not sure why it's creeping downward. But, since it is I'm going to use this as an opportunity to lower my alk from 120 to 100. I am wondering which works better. Rippling the water or big fountain. My returns are not directional so I am using a fountain that plugs into the return line that runs the RayVac. The fountain has two heads that can be used. One is low and just ripples the water whereas the other shoots the water in the air in three tiers. Which do you think would work best (or fastest)?

Here's my numbers for reference.

21 x 40 Concrete pool, 25,000 gals.
FC: 6.5
CC: 0
TC: 6.5
ALK: 120
CH: 240
CYA: 50

Thanks.
Dianne

[mwsmith2]

I don't think I'd worry about Reducing 120 alk to 100. 100 is getting toward the low side anyway. It's fine as is.

However, to answer your question, the best way is the one that areates the water the most.

Michael

[dhale1]

Thanks for the fast reply. I was going to lower it only since I need to bring the PH up a little but do not want my ALK to go up with it. I figured if I lowered it to 100 or 110, then when I add the borax the ALK won't go up past 120. My PH right now is about 7.2 and I'd like to get it up to 7.4 and keep it there.

[aylad]

Your alk shouldn't go up appreciably if you use Borax, and even if it does go up slightly, it still will be fine. As long as it's below 150 or so, I wouldn't worry about it.

Janet

[CrisL]

It's true that borax will not appreciatively raise your alkalinity. However, the aeration should raise your ph while lowering the alkalinity somewhat. If you want to try the aeration, i would go for it.

[CarlD]

OK,

You're getting good advice, but there's a catch: The aeration doesn't lower your Alk, it raises pH without raising Alk.

Alk tags along with pH normally. You lower your pH, Alk comes down with it. pH goes up, normally Alk does too.

So you lower your pH to 7.0-7.2. Then measure your Total Alkalinity (so you know where you are). Then you aerate to raise pH without Alk going up. If Alk is OK, you are done. If still high, you lower pH again, dragging down Alk with it, and aerate to raise it.

It's a little confusing to say that Borax doesn't raise Alk and that it does. But both are true. When Borax raises pH, Alk will rise correspondingly. This is different than Soda Ash (Bal Pak 200, or pH Up) which will not only raise pH, but will increase the Alk even more so. So if you raise your pH with Soda Ash to, say, 7.8, your Alk will go up a good bit more than if you raise it with Borax.

But aeration (for reasons I barely understand and cannot explain) raises the pH without raising the Alk at all.

Hope this helps....

[Poconos]

Dianne,
At a TA of 120....don't worry. Leave it alone. But, to answer your question, fountains or anything that sprays water is a better aeration mechanism.
Al