Alkalinity?

[savdoc2]

I know that lowering the alk is a slow process.

We uncovered the pool a little over a week ago 4/23. Was a little green so added bleach until I got a reading over 5 - that is the limit of the HTH drop kit I got at Walmart (can't wait for Ben's kit to come). I tested tonight and CL (it only tests TC) is still bright orange - off the chart.

I have a 14K gal AG pool and my numbers are:

TC = 5+
pH = 7.2
Alk = 190 (a purple color down from 240+ on the 23rd)
cal = 260
CYA = 40

I have added a bunch of dry acid and I still maintain a constant pH reading, but Alk is slowly going down. On the 26th, we added 7lb dry acid (dissolved in water), and again on the 27th. It has been raining the last few days, so I didn't get back out there to add more. We are aerating unconventionally, but it is working. We have a sump pump in the water with a hose attached to a spray nozzle and balanced on the edge spraying into the water like a fountain would.

Does this sound like we are headed down the right track? The alk test really changed color with fewer drops tonight, but is still very high. I will put another round of acid in tomorrow morning. It seems like I am really using a lot of acid. I haven't been able to find liquid muratic acid, or I would use it instead of the dry acid.

Any thoughts or advice?

[jenmenke]

Look for the liquid muriatic acid at a regular hardware store, usually near the paint. It's about $3-4/gallon around here.

I can't respond to your chemical questions, but look at the thread titled "lowering Alk -- fountain or ripple." http://www.poolforum.com/pf2/showthread.php?t=783

It has lots of similar info you are looking for. I'm in your same boat: high Alk, low Ph. I'm doing what you're doing and no one has said NO!!! STOP!!! So that's a good sign, I guess.

(I've added 2 gallons of acid to my 40,000 gal IG vinyl pool and I've lowered it from about 250 to 160-170 over the weekend. Ph is lower, but I'm aerating too, hoping to bring it back up. Have no idea how long that takes, tho...)

Jennie

[duraleigh]

Jennie and "Doc",

You each get a Gold Star!! IMHO, lowering alk thru aeration is a high level of understanding how your pool chemistry works. I cannot tell you how long it will take.....there's lots of variables perhaps most importantly how agressive you can get with aeration. HD/Lowe's has muriatic in the paint section.....pricey, tho.

Doc, you can dilute your pool test water by 1/2 with distilled. The Cl test will then double in value. (reading of 4 means you've got 8ppm) You could even dilute it by thirds and should be able to test reasonably well up to 15ppm. Ben's kit will remove any remaining unhappiness in your pool life!!

I'm pretty sure Ben has a sticky posted at the top of the "alkalinity" forum called "Step-by-step....." Check it out.

[savdoc2]

I did read the sticky on how to lower alkalinity and that is what I am following.

A quick question about the liquid muratic acid: Is there an equivalency between liquid muratic acid and the dry acid? In other words, how much muratic acid should I add at each time?

[aylad]

I think you'll find that it takes less muriatic acid than dry to get the job done, but there's not really an equivalency between the two....just add enough muriatic acid to get your pH down to the 7.0 - 7.2 range. mwsmith has a calculator at this link http://www.hal-pc.org/~mwsmith2/BleachCalc262.exe
that can help you figure out how much to add, based on your current pH.

Janet

[savdoc2]

I just don't get it.

How can I keep adding acid and still get no drop in pH or Alk? I put in the last 7 lbs of dry acid about 4 hours ago and there is no change in either reading. I did buy some muratic acid at Lowes this afternoon, so as soon as my husband gets home I will add some of it and let it work overnight.

[waterbear]

I think I see what the problem is. I just noticed your chlorine levels are well above 5 ppm (bright orange on OTO test!) . If they are very much above about 10 then when you test pH the phenol red indicator is being converted to chlophenol red which is an indicator for a lower pH range! (some indicators are better than others...i.e. have a chlorine neutralizer built in, but this will only work to a point and some conversion of phenol red to chlorphenol red will still occur at high chlorine levels) It is entirely possible that your pH is below 6.0 now if your chlorine levels are very high! the color that chlorphenol red prduces at a pH of about 5.4 is similar to the one that phenol red produces at about 7.2! I suggest that you get your chlorine done at a pool store that uses an FAS-DPD titraton test (or buy such a kit yourself) and find out just how high your clorine level is. If it is above about 10 ppm then you should treat you pH readings as suspect until it drops down.

you will not see a deacrease in alkalinity until the pH starts to climb above about 7.4 so it might take airating for a while, given the low pH.

IMHO, I would not add any more acid right now until the CL levels drop to normal ranges.

First thing is to wait for the CL levels to drop below about 8 ppm and then test the pH. Once you know where it is then you will have a better idea what to do next!

[savdoc2]

Thanks for that explanation. I have Ben's kit ordered, so I hope it comes soon.

I am really surprised that my CL levels have stayed so high. I did wonder about the high CL bleacing the indicators. I will see if a local dealer does a titration test tomorrow.

[mphare]

On of the pH drop test kits I have has a chlorine neutralizer that should be added when the CL level is high.

Isn't one of the solutions in the Taylor2005 also a CL neutralizer? Maybe you just need to add more neutralizer before measuring pH.

[CarlD]

Just to clarify:
Aerating does NOT lower alkalinity (TA). It raises pH without raising TA--and nothing else can do that.

When you lower pH, you drag TA down with it. If you raise pH with soda ash or borax TA will rise--more with ash than borax. So you aerate to raise pH.

So the process is a racheting process. Lower pH and drag TA down with it. Raise pH with aeration. Repeat until TA is where you want it.