Should I lower my pH?

[MT]

Tested last night and here is what I had...

FC - 6.5
CC - 0.5
pH - 7.8
TA - 120
CH - 120
CYA - 110

I am losing 1 - 1.5 ppm FC overnight. I want to keep FC at 7 - 7.5 while I work on getting my CYA down, but can only do small water replacements with well water so it will take a long time. Looks to me like I should lower my pH, no? I'm going to aim for pH of 7.5.

What do you think?

 

[duraleigh]

MT,

Keep your questions under one thread. Responders get very confused when you start too many threads.

 

[MT]

You mean my recent questions about muriatic acid and borax shelf life? Or my last post with test results? Should have all been on same thread?

 

[msgtdan]

I usually lower at 7.8, because I have high TA fill water I know it's going to go back up so I go down to 7.2.

 

[MT]

Ok, I have a PROBLEM now and need some help. The pool has a slight green tinge to it. It is still clear, but NOT blue.
I think I was dumb to keep the FC around the MINIMUM (FC - 7 ppm) instead of what is the recommended target (FC - 12 ppm). As soon as I noticed the slight green look, I put in a bottle of bleach. After about 15 minutes of circulation, these are my test numbers:

Currently:
FC - 11
CC - 0
pH - 7.6

as of yesterday:
TA - 120
CH - 110
CYA - 110

What should I do? The two things I changed in the past few days are:
1. Stopped running my pump 24 hrs. Started running 12 hrs per day 10am - 10pm.
2. Let the FC level drop below 7 ppm. I know one night it was at 6 ppm.

I have people coming over tomorrow to swim. I want to fix the issue, but I'd like the pool to be swimable. Thanks in advance all!

 

[JasonLion]

I would run the FC level up to shock level right away. With high CYA levels it is very very difficult to recover once things start sliding out of control. Your best chance is to hit it hard as quickly as possible before things get out of control.

Maintaining a pool with CYA at 100 or higher is very problematic. I strongly recommend replacing water to get the CYA level down to something more reasonable. Also, keep in mind that none of the CYA tests are capable of very much precision when measuring levels over 100, so your CYA level could easily be quite a bit higher than you think it is (or lower).

 

[MT]

I know its not the smartest thing to do, but I don't want to shock it until tonight because I;m having people over to swim today. It is a very very slight tinge of green. It is hardly noticeable, but I notice it. Last night I brought FC up to 17 ppm, CC was at 0.5.

This morning, green tinge is no better, no worse. FC is 15 ppm and CC at 0.

I figure since my CYA is so high, I'm due for a large water replacement anyway. So if it get's worse over the next 12 hrs before I can shock it, oh well.

 

[duraleigh]

You mean my recent questions about muriatic acid and borax shelf life? Or my last post with test results? Should have all been on same thread?

Yes. When you are a responder, it is difficult to keep track. If you start too many threads, responders will simply skip your threads rather than try to sort them all out.

 

[MT]

Evening of July 3rd, I put enough bleach in to get the FC up to 17 ppm. Early yesterday morning, July 4th, FC level was at 15ppm. Pool water looking better, went from slightly noticeable green tint to almost no green tint. I brought the FC back up to 17 ppm.

Had a July 4th party, bunch of people swimming in the pool all day. That night, FC tested at 10 ppm. So I decided to shock it (or close to shock levels). I added enough bleach to bring the FC up to 28 - 30 based on pool calc. But silly me, forgot to lower the pH first.

This morning:
FC = 28.5
CC = 0
pH = 8.2+ ?

After getting the above results, pool looks good but not crystal clear like it was a week ago. I dumped a good amount of muriatic acid in before I left for work to lower the pH but did not have time to stick around and test its effect.

My plan this evening is as follows, any comments welcome:

1. Test the pH, FC, and CC.
2. If pH is still too high, put in more muriatic acid (how low depends a bit on FC level).
3. If pH is way low, too low for bleach addition to help, I'll add borax.
4. As long as my CC is still 0, I plan on aiming for my FC to be 12 ppm. If FC tests higher than 14 ppm I will not add any bleach tonight.
5. Test FC again before bedtime and tomorrow morning calculate my FC loss.

Am I headed in the right direction?

 

[JasonLion]

The PH test results are invalid when FC levels are that high. You should ignore PH readings unless FC is 10 or lower.

Since you have been adjusting the PH when the test results are invalid, chances are your have lowered the PH well below where it should be. You should make a point of checking and adjusting the PH as soon as the FC level gets down to something more reasonable, and in the meantime stop adjusting the PH. (This is but one of the many many hazards of trying to get by with high CYA levels.)

 

[MT]

Oh man I forgot about that! So now what should I do? Let the FC naturally drop down to 10 ppm or a little lower so I can get an accurate pH reading. Then adjust pH. Then bump the FC back up to 12 ppm?

Does this mean don't swim in the pool until I have accurate pH test results?

 

[JasonLion]

The whole situation is problematic. The FC level won't come down any time soon, so you are kind of stuck.

As I said before, you should replace water to get the CYA level down to something more reasonable, which would eliminate this problem.

 

[MT]

ok, so help me out with water replacement. not sure I'm committed to this yet, but it seems inevitable. My pool is ~ 23,000 gallons. A truckload of water carries 6,000 gallons. So I'd need two truckloads to do a 50% change.

How do I drain my pool enough to know I can take the full 12,000 gallons, without draining it too much that I'll have a hard time making up the difference with well water?

My pool has a main drain in the deep end and I can pump thru filter to waste.

 

[MT]

Test results this evening:

FC - 21
CC - 0
pH - 7.2
TA - 120
CYA - 100

With the combo of high CYA, 8 ppm FC loss, the added muriotic acid, could I possibly be getting an accurate pH reading? The pool looks very clear and blue now. I'll check overnight FC loss to make sure I'm good. But at least I'll feel safe swimming tomorrow. Probably going to let FC make its way down to 10 - 12 and see how much daily bleach it takes to keep it there. I'll raise the pH up to 7.5 after the FC works its way down.

But of course water replacement at least 50% is in my future, so I'm still looking for advice there.

 

[MT]

I'm pretty sure the green tint has something to do with my well water. After shocking and being perfectly clear and clean for a week or two, I drained about 4" of water from the pool and re-filled with well water. The same green tinge came back! Then it just goes away by itself within 24 hours.

What could be in my well water that is having this effect? It is a VERY VERY slight tinge of green, hardly noticeable but there.

 

[Bama Rambler]

A few people here have reported the same occurance. It's most likely metals and either enough of them are getting filtered out or they initially react to the chlorine.

If you're still looking at replacing half of the water you can get a sump pump and a hose water meter and pump out a little more than the amount you want to replace and then have water trucked in.

 

[MT]

Ahh.. hose water meter, that should do the trick.