Is there a certain window of time

Thanks!

I think my rapidly escalating PH was related to the air bubbles in my return line.

Apparantly it's a very effective aerater, since I run my pump 24/7 :(

Now that that's fixed, I may just leave things alone and see if my PH holds steady. 14-150 in a vinyl lined pool should be fine.

Quote:

---

Originally Posted by Rangeball

Ben's sticky says you need to get PH low to induce carbon dioxide production.

Once carbon dioxide is present, I assume it's no longer measurable as part of the ALK test, and this is why we get the drop, right?

And if it's not gassed off, when PH increases due to aeration, carbon dioxide reverts back to CA, which is measurable, right?

Anyone know at what PH level carbon dioxide re-converts to CA? Waterbear?

---

Exactly right, except that the incease in pH is due to the CO2 being gassed off...as there is less carbonic acid the pH will rise but the buffer is in equalibrium so things shift as the pH rises..It takes a bit of time and patience to lower TA. pH determines the ratio of carbonic acid to carbonates/bicarbonates in the water.....lower pH means more carbonic acid and less measurabe TA. Higher pH is the reverse. If you remove the carbonic acid by gassing off the CO2 you have lowered the TA because you have less of the total buffer system in the water. As you you lower the carbonic acid the carbonate/bicarbonate try to reach a new equalibrim so they lower. The purpose of a buffer is to stabilze pH so the pH will rise as the equalibrium is reached. The net effect is a lower TA. In most pools the TA buffer will stabililize at a pH of around 8 so the addition of acid to keep the pH in range is still necessary.

Thanks Evan. I think I finally have my head wrapped around this.

I'm 100% certain my difficulties have been from aerating WHILE trying to lower PH. Doesn't work, for me.

Now that I made progress and can live with the result, I noticed I'm down about an inch of water from evaporation (and probably my splash out from the cannon balls), and dread having to refill soon.

The guy that runs our town's water plant was in my office a few days ago. I asked him if our alkalinity always runs high (320 when I tested, with a PH of 7.2). He said yes :(

I have a vinyl lined pool. If I followed Ben's "Run a high PH" page, I'll end up over 8 with an alk in the mid 250s.

Is this a problem at all if I just let the pool do what it wants? What would I be risking?

Tested again this noon just to see where I'm at. Haven't aerated since yesterday morning.

PH was 7.2.
Alk was between 130-40. I didn't wait long enough between the drops, and the 130 drop may have been enough. I'll call it 135 :)

Since I'm this close to a good alk goal, the PH is still low and all my air leak issues seem resolved, I may go ahead and lower my ALK some more as I'm anticipating adding water again in a week or so. That way when I do hopefully I can keep alk under 200 and not worry about this much.

I'm out of acid. I guess the deciding factor will be how soon I go get some :)

We had a good rain a few days ago. Apparantly rain provides good aeration, as my PH is back up to 7.6 :)

My youngest daughter and I got in last night, and I was suprised at the amount of carbon dioxide still being released (you can see it if you wash the air bubble release after a dive or jump in). Apparantly, 7.6 is still low enough that carbon dioxide does not reconvert to carbonic acid.

I'm about 2.5" low on my water level now (we didn't get that much rain, and desperately need it :( ), so I may be forced to fight this battle again soon.

Quote:

---

Originally Posted by Rangeball

We had a good rain a few days ago. Apparantly rain provides good aeration, as my PH is back up to 7.6 :)

My youngest daughter and I got in last night, and I was suprised at the amount of carbon dioxide still being released (you can see it if you wash the air bubble release after a dive or jump in). Apparantly, 7.6 is still low enough that carbon dioxide does not reconvert to carbonic acid.
Just to claify...carbonic acid is carbon dioxide dissolved in the water. You alway have carbonic acid/carbonates/bicarbonates in the water...the pH just changes the proportions of each.
I'm about 2.5" low on my water level now (we didn't get that much rain, and desperately need it :( ), so I may be forced to fight this battle again soon.

---

hope this is helpful.

Thanks, it was.

I was confusing CA, ie carbonic alkalinity with Carbonic Acid, ie carbon dioxide.

Since they both are CA it confused me :)

Quote:

---

Originally Posted by Rangeball

Thanks, it was.

I was confusing CA, ie carbonic alkalinity with Carbonic Acid, ie carbon dioxide.

Since they both are CA it confused me :)

---

The proper abreviation is kH for carbonate hardness (the German form is used so it is not confused with calcium hardness)! NOt used much in the pool industry however.