Cannot get pH level to lower and stay that way

[crackertastic]

I am having some trouble getting my pH levels to stay down. My water chemistry is a bit out of order at the moment, all the numbers I am after are steadily coming in line as I add chemicals, but pH simply won't stay down. I am using a TF-100 to test my water samples.

My FC has been high, but is now falling. I believe this is because the titanium electrode in my SWG has gone bad (new one on order) and may have been going overdrive on chlorine production before its death. I never actually added any chlorine to the pool manually and our city water has high chlorine to begin with so that could be the reason also. TA in the water is also VERY high, but it is also falling slowly. CYA was low (despite stupid test strips - so glad I bought the TF-100) but I have that on the rise as well.

Here are readings from three different days:

5/28:
FC - 8.0
CC - 0.5
TC - 8.5
CH - 450
TA - 240
CYA - 22
pH - >8.2 (The pinkish hue of the water was more vibrant than the top square on the tester.)

At this point I added some stabilizer, about 3.5 lbs, and about a quart of muriatic acid.

5/29:
FC - 7.0
CC - <0.5 (Pinkish hue of the water was barely noticable.)
TC - <7.5
CH - 450
TA - 210
CYA - 45
pH - >8.2

I didn't add any extra CYA at this point since the stuff allegedly takes some time to register on a test. I did however add two more quarts of muriatic to the pool.

5/31:
FC - 5.0
CC - 0.0
TC - 5.0
CH - 400
TA - 180
CYA - 48
pH - >8.2

I don't really understand why the muriatic acid is not getting the pH level down. When I add some I wait about an hour or so and test it and the level is about 7.5, but 24 hours later is has skyrocketed again. I understand it isn't going to move much because of my TA level being so high. But now since I have that coming down I would suspect I should see some kind of small change.

I'm going to check my CYA levels over the next couple of days to see if it rises any more before adding more stabilizer. Water is currently crystal clear. I've been vacuuming anything that settles to the bottom and skimming off anything on top of the water with my net.

Any ideas to help get my pH down - and keep it down?

 

[jblizzle]

Are you using PoolMath to calculate how much acid to add? Make sure your TA in entered too.

Your TA is very high, so that is going to drive the pH up. Also SWGs cause aeration that also drives the pH up.

 

[crackertastic]

No, I wasn't using PoolMath to do the calculations. I've been adding in increments and testing. Thanks for that link.

According to that link, using results from my first test, I've already added more than double what I need to add in order to get the pH down to 7.5. I've added about 96oz of muriatic acid and the calculator recommends 46oz. Of course the calculator says it may be off "significantly" on its calculation for large pH changes, so maybe I need to add the rest of what I have in muriatic acid and see where that gets me.

Is it safe to say that until I get my TA down (via the muriatic acid method) my pH is going to continually go up even after I lower it? Is it possible to add too much pH reducer at once? I have a full bottle of dry HTH pH Minus that I haven't even opened up.

 

[tim5055]

Pool Math is not going to be able to give you an exact amount because you only know that it is greater than 8.2. Until you get it down into the measurable range it's anyone's guess.

Even after you get your TA under control the pH will probably still rise over time, but it will be a slower more controlled rise.

 

[Richard320]

Is it safe to say that until I get my TA down (via the muriatic acid method) my pH is going to continually go up even after I lower it?

Yes, exactly.

Your TA is going down, so you're making progress.

Plug your numbers into poolmath. Let it calculate the dose of acid to lower your pH. Then go way down to where it says Effects of Adding Chemicals and plug that amount in and it will tell you roughly how much pH will drop and how much TA will lower. It won't be exact; you're at the top of the pH scale, so you might be above 8.2, but you'll see how it works.

Acid lowers pH and TA. Time, SSWG, and aeration all push pH up again without affecting TA. It's sort of a ratchet effect. pH is the wrench, TA is the nut. You turn the ratchet when you lower pH, and the TA moves. Then the ratchet swings back up but the nut stays put.

 

[crackertastic]

Thanks for the clarification Richard. Nice analogy also.

Judging by the numbers on PoolMath I still have quite a ways to go it would seem. Now that aeration is mentioned, where the water returns to the pool the level is covering the jet stream about halfway. I have the eye pointed downwards, but that may still be helping with aeration.

 

[crackertastic]

Just to follow up, yesterday I added the remainder of my muriatic acid, which was about a quart, and all of my dry pH minus, about 7 lbs. Based on PoolMatch calculations would have dropped the pH significantly and reduced the TA by about 60 ppm. That would at least get me into the high end of a semi-acceptable range. After adding all of this I checked the pH about 2 hours later and it had dropped below 6.8 - the lowest it has dropped in general. TA didn't move at all.

I also added enough water to go above the return jet so there is now no water skimming across the top of the pool. Instead the return is pointed downwards and is completely submerged. This should stagnate the pH rise since now I've taken away a major source of aeration.

So just a short while ago it is now 24 hours later and I decided to take another full reading to see where I stand.

FC - 4.0
CC - 0.0
TC - 4.0
CH - 400
TA - 180
CYA - 63
pH - 7.2

So now this is odd, my pH has dropped a bit and is staying down, but TA didn't seem to move at all. Can anyone provide some insight as to what gives? Does an attempt to make a big change in TA all at once take some time to register?

 

[Richard320]

Just to follow up, yesterday I added the remainder of my muriatic acid, which was about a quart, and all of my dry pH minus, about 7 lbs. Based on PoolMatch calculations would have dropped the pH significantly and reduced the TA by about 60 ppm. That would at least get me into the high end of a semi-acceptable range. After adding all of this I checked the pH about 2 hours later and it had dropped below 6.8 - the lowest it has dropped in general. TA didn't move at all.

I also added enough water to go above the return jet so there is now no water skimming across the top of the pool. Instead the return is pointed downwards and is completely submerged. This should stagnate the pH rise since now I've taken away a major source of aeration.

So just a short while ago it is now 24 hours later and I decided to take another full reading to see where I stand.

FC - 4.0
CC - 0.0
TC - 4.0
CH - 400
TA - 180
CYA - 63
pH - 7.2

So now this is odd, my pH has dropped a bit and is staying down, but TA didn't seem to move at all. Can anyone provide some insight as to what gives? Does an attempt to make a big change in TA all at once take some time to register?

Test your tap water. I'll bet it has high pH and high TA.

 

[crackertastic]

Hey Richard,

Did as you suggested, here's what I came up with

FC, CC, TC - 0.0
TA - 350
pH - 7.2

I tested the water from the spigot running out of my house, which is the same place the pool water came from. Not sure if it matters but I did a complete refill, when I opened up the pool this year. Completely drained it, scrubbed it, sprayed it and filled it back up.

Do those numbers above make any sense? I though TA and pH where kind of hand in hand so to speak. It would seem like everything I've done so far only brought down my TA by about half and put the pH back to where it is at normally. I'm guessing these past few weeks of the water skimming across the top of the pool was a contributing factor to my high pH levels.

 

[Richard320]

Hey Richard,

Did as you suggested, here's what I came up with

FC, CC, TC - 0.0
TA - 350
pH - 7.2

I tested the water from the spigot running out of my house, which is the same place the pool water came from. Not sure if it matters but I did a complete refill, when I opened up the pool this year. Completely drained it, scrubbed it, sprayed it and filled it back up.

Do those numbers above make any sense? I though TA and pH where kind of hand in hand so to speak. It would seem like everything I've done so far only brought down my TA by about half and put the pH back to where it is at normally. I'm guessing these past few weeks of the water skimming across the top of the pool was a contributing factor to my high pH levels.

Want some fun with science? Fill an empty bottle with that sample and shake it up really good, like you'd do if you wanted to make a can of Coke explode when someone opened it. Then test pH.

 

[crackertastic]

I like having fun with science!

So I did as you asked - and the winning number is - 7.2

Not sure if I was to be expecting a change. While I was at it I tested the pH of the water coming out of my sink faucet. Approx. 6.8 - 6.9

I suddenly feel like all the stuff I was learning in Pool School is getting turned upside down.

 

[Richard320]

I like having fun with science!

So I did as you asked - and the winning number is - 7.2

Not sure if I was to be expecting a change. While I was at it I tested the pH of the water coming out of my sink faucet. Approx. 6.8 - 6.9

I suddenly feel like all the stuff I was learning in Pool School is getting turned upside down.

Not at all. Start with tap water and shake it up. Make sure you leave some air in the bottle. Aeration raises pH. It'll do it.

 

[crackertastic]

I still had the water sample I was working this in the bottle. It did have some air in it already, first time I shook it was for a short period of time.

This time around I shook it for a few minutes. The pH level came up to 7.5. Capped the bottle again and continued shaking until my arms got tired, but I couldn't manage to get much past that.

 

[Richard320]

I still had the water sample I was working this in the bottle. It did have some air in it already, first time I shook it was for a short period of time.

This time around I shook it for a few minutes. The pH level came up to 7.5. Capped the bottle again and continued shaking until my arms got tired, but I couldn't manage to get much past that.

See? Aeration works! You didn't add anything, yet the pH rose.

 

[crackertastic]

Well Richard, you have definitely proven yourself as a water pharaoh! :farao: My arms appreciate the workout. That was a neat little experiment.

However, got any advice on my TA levels that seemingly won't budge. Muriatic acid and the HTH pH Minus are both supposed to lower TA, yet it went nowhere. What should I do at this point? Do I keep dosing the water with muriatic acid while aerating the pool to get the TA down while keep the pH from going too low?

 

[Richard320]

Well Richard, you have definitely proven yourself as a water pharaoh! :farao: My arms appreciate the workout. That was a neat little experiment.

However, got any advice on my TA levels that seemingly won't budge. Muriatic acid and the HTH pH Minus are both supposed to lower TA, yet it went nowhere. What should I do at this point? Do I keep dosing the water with muriatic acid while aerating the pool to get the TA down while keep the pH from going too low?

The stuff's not toxic. You drink that same fill water and bathe in it, don't you? Just sigh wistfully and accept that you'll be dosing with acid almost as often as bleach. It WILL go down eventually. Just keep the pH in range and it doesn't really matter what TA is.

 

[crackertastic]

Okay, well that sounds simple enough to manage. I will stop by the local hardware store and pick up some more acid and start bring the TA down little by little.

I see you made the mention of bleach. That shouldn't be necessary with my SWG, right?. I know my FC is slowly declining per the readings I've been giving, but that is because my SWG isn't generating any chlorine at the moment due to a faulty titanium electrode. The replacement piece is on its way, but Intex likes to choose the SLOWEST possible shipping method at their disposal when sending replacements. I do have some bleach on hand specifically to keep FC in check for when it drops too low. Before the electrode went my SWG was keeping the chlorine about 4-ish. I added some HTH super shock when the electrode broke to give the water a head start in keeping up with sanitization. Since my CC is staying at zero I not too worried that something is starting in the water, but I've been keeping an eye on that and testing every day. The water also has an algae prevention additive in there as well.

 

[Richard320]

Okay, well that sounds simple enough to manage. I will stop by the local hardware store and pick up some more acid and start bring the TA down little by little.

I see you made the mention of bleach. That shouldn't be necessary with my SWG, right?. I know my FC is slowly declining per the readings I've been giving, but that is because my SWG isn't generating any chlorine at the moment due to a faulty titanium electrode. The replacement piece is on its way, but Intex likes to choose the SLOWEST possible shipping method at their disposal when sending replacements. I do have some bleach on hand specifically to keep FC in check for when it drops too low. Before the electrode went my SWG was keeping the chlorine about 4-ish. I added some HTH super shock when the electrode broke to give the water a head start in keeping up with sanitization. Since my CC is staying at zero I not too worried that something is starting in the water, but I've been keeping an eye on that and testing every day. The water also has an algae prevention additive in there as well.

I must have missed that part. My mistake. On the other hand, maybe my mistake was meant to be; if the SWG isn't generating, you've got a bleach pool. You need to maintain it as such.