A bit confused

[Cal_Newbie]

eeeeeeeeeek.......not having fun here.

OK, get the CC to 15ppm...no problem. Get FC to 0, ok. I need to get the Alkaline below 200, so adding acid in small amounts and bubble the water will work that down.... how often shall I check on this process?

[CarlD]

eeeeeeeeeek.......not having fun here.

OK, get the CC to 15ppm...no problem. Get FC to 0, ok. I need to get the Alkaline below 200, so adding acid in small amounts and bubble the water will work that down.... how often shall I check on this process?

You STILL have it backwards: CC is Combined Chloramines...you want THAT at 0. FC is Free Chlorine, the good stuff--free to attack any NEW contaminants. You want THAT at 15. You raise FC by adding chlorine or bleach. There is no way (or reason) to raise CC.

Lowering alkalinity is a simpler process than it sounds if when you know what the steps do. Add the acid to lower pH to 7.0 to 7.2. DON'T GUESS! Below 6.9 will damage vinyl, above 7.2 won't work.

Now, when you lower pH, it pulls the T/A down with it. The bubbling (aerating actually) is the ONLY way to raise pH without raising the T/A as well.

Then, when pH is back over 7.2 (anything from 7.3 on up) you add acid again to lower pH BACK to 7.0 to 7.2 and keep bubbling!

I would check pH a couple of times a day, but I would only check T/A once a day (like about every 2 acid cycles). That's merely a guess and a suggestion. You can measure them both more as long as your test chems hold out.

Don't worry about T/A going too low. From 240 to below 80 will take several days. Besides, lowering T/A is a pain, but there's NOTHING to raising it! Just add some baking soda--regular Arm&Hammer.

When your T/A is good (and I would NOT stop at 200, I would go to a much lower level) you can then raise pH where you want it by adding Borax --20 Mule Team Borax.

[Cal_Newbie]

roflmao....I am so sorry Carl, vicoden and pool chemistry are bad, bad, bad combo...had shoulder surgery so I am a bit out of the loop still. Got it, FC, FC, FC.... heads a bit clearer this morning........again, I apologize but I did get a good laugh.. now where is my power saws??

Bob-

[Cal_Newbie]

OK, so it has been a number of days while I have been working the PH down with acid and I am in the range I need to be, 7.0-7.2.

Should not the TA be down also? I inquire because my TA is at 250ppm. I used my Taylor Kit at the 10ml mark, added the drops accordingly to the directions annd it took 10 drops to go from green to red and multiply x 25 = 250ppm.

What gives? Do I need to take it lower still, the PH that is? I realize that below 7.0 there is significant problems on a vinyl..so please direct me as to what to do next. I thought I had this doggy whipped...

Bob-

[chem geek]

Bob,

To lower your TA follow Ben's Lowering Your Alkalinity procedure precisely. You are already at the low pH so you need to aerate your water in any way that you can -- point jets upwards, run waterfalls or other features that would aerate the water, put in a recirculation pump and hose that splashes into the water, get an air compressor and put a nozzle at the end of the hose that creates tiny bubbles and put this into the deep end of the pool, have a bunch of kids (or fun adults!) over splashing in the pool, etc.

As you aerate, the pH will rise so you'll need to add acid to keep it in the 7.0 to 7.2 range. After a while of doing this, measure the TA level and when it gets to where you want it (probably under 100 ppm), then you stop adding the acid and just let the pH go up to where you want it (probably around 7.5).

Richard

[Cal_Newbie]

Richard,

So even where my TA is at this time, I can go ahead and aerate? That I can handle. How often shall I test the water PH?

Thank You,

Bob-

[chem geek]

Bob,

I'm not sure what you mean by "even where the TA is at this time" since your TA is definitely too high. You can most definitely aerate. As far as how frequently to check pH, I can't tell you that because it really depends on how effective your aeration is. Just test it after a few hours and if it's not changing very much you can check on it less frequently, but when it goes up measurably (say, from 7.2 to 7.4) you can add acid to bring it back down. I assume you may have an acid demand test to tell you how much acid to add, but I can give you a rough idea BUT it depends on your TA level so as the TA gets lowered it will take less and less acid to bring the pH back down from 7.4 to 7.2. If your pH test reliably tests down to 6.8, then you can use 7.0 as your target or 7.1 which would be in between the 7.0 and 7.2 colors on your test. The point is that this process is more effective at lower pH, but don't worry that being right near 7.0 is going to somehow destroy your vinyl -- it won't. You just don't want it to get much below 7.0, that's all, so using 7.0 or 7.1 as your "target" during this process is fine.

As an example for your 9600 gallon pool, when the TA is at 250 ppm it takes 26 ounces or 3 cups 2 ounces of Muriatic Acid to go from a pH of 7.4 to 7.2 (43 ounces or 5 cups 3 ounces to go from a pH of 7.4 to 7.1).

For comparison, at a TA of 150 ppm it takes 16 ounces or 2 cups to go from a pH of 7.4 to 7.2 (27 ounces or 3 cups 3 ounces to go from a pH of 7.4 to 7.1).

For technical reasons it takes less acid to lower the pH in a higher pH range than in a lower pH range, so trying to get to a much lower pH gets progressively harder -- kind of like pulling on a spring. That's why the amount of acid to get to 7.1 compared to 7.2 seems to be more than one might expect.

Richard