Progress finally, or The TA battle...

[steveinaz]

Ok, after multiple slams of acid this evening (and thanks to my waterfall for aeration) I've made serious progress in the battle of the high TA. Some numbers:

FC=5.5ppm
CC=0ppm
pH=7.5 (before slamming to 7.1)
CYA=90ppm (oops...updated reading tonight after 5 days of circulation)
TA=120ppm (uncorrected for CYA)...down from 180ppm 8 days ago
TA=93ppm (corrected for CYA, 30% factor)
CH=710ppm (yeah, yeah, I know. This is a battle for another day)

My grandmonkies will help me via "splashout" on the over-shoot of CYA, this weekend...plus, I have one of those pools that mysteriously looses CYA over the winter, so I'm not too concerned about it. I did up my SWCG output to 75% to compensate, which usually puts me at 6-8ppm FC this time of year.

QUESTION EVAN:
Should I be looking at corrected TA for my target of 80ppm, or uncorrected? Uncorrected would make my target 110ppm TA...

I was gonna slam it one more time with acid this evening, but a 7.0-7.1 pH made me wait until tommorrow. I should be golden after that. Oh, and...the snowflakes are gone.

[waterbear]

Ok, after multiple slams of acid this evening (and thanks to my waterfall for aeration) I've made serious progress in the battle of the high TA. Some numbers:

FC=5.5ppm
CC=0ppm
pH=7.5 (before slamming to 7.1)
CYA=90ppm (oops...updated reading tonight after 5 days of circulation)
TA=120ppm (uncorrected for CYA)...down from 180ppm 8 days ago
TA=93ppm (corrected for CYA)
CH=710ppm (yeah, yeah, I know. This is a battle for another day)

My grandmonkies will help me via "splashout" on the over-shoot of CYA, this weekend...plus, I have one of those pools that mysteriously looses CYA over the winter, so I'm not too concerned about it.

QUESTION EVAN:
Should I be looking at corrected TA for my target of 80ppm, or uncorrected? Uncorrected would make my target 110ppm TA...

I was gonna slam it one more time with acid this evening, but a 7.0-7.1 pH made me wait until tommorrow. I should be golden after that.

You want an uncorrected TA of 80 ppm or possibly even less with your waterfall if you are planning to add the borates, which I highly recommend.
Don't even mess with computing the corrected reading, it's just a waste of time.

Don't worry about the overshoot on the CYA. Even 100ppm is workable in Arizona with a SWG, especially given the high CH in that area, since it might allow you to run at an even lower output percentage and thereby get better pH control and thereby less chance of scaling conditions (particularly if you run the waterfall).

[steveinaz]

Thanks for the advice. I'll continue wailing on the TA tommorrow. The borates will have to wait until after the partial drain this fall to get rid of excess CH.

I don't usually use the waterfall---but it did do a great job of boosting pH for me this evening!

Really appreciate the assist Evan. You the man.

[waterbear]

Thanks for the advice. I'll continue wailing on the TA tommorrow. The borates will have to wait until after the partial drain this fall to get rid of excess CH.

What is the CH of your fill water? I was under the impression that AZ had very hard water. Unless your fill water is much lower in CH then partial drain is not going to do much good and you might have to lower TA again if you fill water has high TA. Realize that the lower the TA the higher the CH can be and still and the water is still 'balanced'.
If that is the case then don't wait on the borates. They make a big difference with a SWG in most cases for a relatively small expense.

[steveinaz]

IIRC, it was about 200-250 from the tap. Our water down here in Sierra Vista is very, very good--far better than Tucsons' chlorine flavored water.

I'll test the tap tommorrow...

[steveinaz]

Didn't make much progress yesterday:

FC=5.5
CC=0
PH=7.5
TA=120ppm (started at 130ppm--drifted up 10 from day before)
CYA=95ppm (retested this to verify)
CH=680ppm (tested this twice yesterday to verify)
Water temp=86

I used a total of 6 cups of muriatic yesterday evening, trying to break that magic 100---I'll do some measurements this afternoon to re-check. Waterfall had my PH from 7.0 to 7.2 in about 2 hrs, so I covered the pool and called it a night at around 7:45pm.

[waterbear]

TA=120ppm (started at 130ppm--drifted up 10 from day before)
Actually, the resolution of this test is 10 ppm so you really have the same result as the day before
CYA=95ppm (retested this to verify)
Still would not lose sleep over this with a SWG in AZ!
CH=680ppm (tested this twice yesterday to verify)
This test is tricky at best. If you are not allowing enough time for the titrant to react or using a magnetic stirrer then it is very possible to overshoot the endpoint, particularly when the CH is high and the titration is taking a long time. I noticed that before you had 710 ppm. Just call it 700 ppm. Next time you might want to try a 10 ml sample. 10 drops of calcium buffer, and three drops of indicator. Then every drop of titrant is 50 ppm CH. When your CH is as high as yours 50 ppm resolution is fine!
Water temp=86

I used a total of 6 cups of muriatic yesterday evening, trying to break that magic 100---I'll do some measurements this afternoon to re-check. Waterfall had my PH from 7.0 to 7.2 in about 2 hrs, so I covered the pool and called it a night at around 7:45pm.

Persistence! Lowering TA sometimes seems to hit a plateau, Keep up what you are doing and you will reach your goal.

[steveinaz]

Yep, I'm in it to win it this time. The hammering will continue this evening!

[steveinaz]

CH of my fill water is 120ppm, I tested it this morning. I think a aprtial drain will be worth the effort. Since I won't be dealing with the added complication of new plaster, dropping TA after re-fill should be a litte easier, right?

5.5 more cups of muriatic last night, TA down to 110 (uncorrected for CYA). I may have finally broken the plateau. Beating on it again this evening. The waterfall really helps with aeration, It brought me from a pH of 7.0 to 7.3 in about 2.5 hrs last night, running full pressure.

[waterbear]

CH of my fill water is 120ppm, I tested it this morning. I think a aprtial drain will be worth the effort. Since I won't be dealing with the added complication of new plaster, dropping TA after re-fill should be a litte easier, right?

Next question, what is the TA of your fill water? You will need about a 50% replacement to get your CH in range from around 700 ppm. You might even need a bit more than that.