Frequency of MA Acid Addition

[JoyfulNoise]

It is a known bug. It has to do with the fact that, under certain conditions of inputs, the carbonate portion (CO2(3-)) of the alkalinity drops close to zero and, for many of the parameters, their log value is calculated. Log(0) = infinity, so the calculation begins to break down. It's only seen in the cases of high borates (which few TFPers use) and very low TA (which is only the case for some plaster pool owners).

Your plaster will be fine. The most likely scenario is that your pool guy will act like a pool guy, think that what they learned in their 2 hour CPO class makes then an expert and then they start dumping all kinds of weird junk in your pool...


Sent from my iPhone using Tapatalk

 

[Naplespool]

It is a known bug. It has to do with the fact that, under certain conditions of inputs, the carbonate portion (CO2(3-)) of the alkalinity drops close to zero and, for many of the parameters, their log value is calculated. Log(0) = infinity, so the calculation begins to break down. It's only seen in the cases of high borates (which few TFPers use) and very low TA (which is only the case for some plaster pool owners).

Your plaster will be fine. The most likely scenario is that your pool guy will act like a pool guy, think that what they learned in their 2 hour CPO class makes then an expert and then they start dumping all kinds of weird junk in your pool...


Sent from my iPhone using Tapatalk

Thanks for the explanation. I looked at the formula in the HTML page source for pool math and saw the Borate term in the equation. I'm going to just tell PM that I have zero borates for now. With that change is seems to track the Taylor Watergram in direction.

Lol, that's what I'm afraid of. I've talked to him once a week for 5 months (while I've handled the chemistry). I believe he'll do what I want. I'm even leaving him a table of how much of each chemical to add for any given shift in readings. At this point my concern is what will happen if the company changes the individual who manages the pool. I think I'm going to train my home watch person to use the Taylor K-2006 once a week.

EDIT: Btw, given our 2" per week average rainfall in the summer, Borate will be down to 25 about 3 months from now.

 

[Naplespool]

Added CYA and Ma on 4/17

late in the day after a few hours of running
FC did not retest
PH 7.3
TA 60
CYA 80 (expected after adding stabilizer)
CH 450
Boric 50
Salt 3600



This morning 4/18 here's what I measured

FC 8.5 ppm
PH 7.4 (up a little)
TA 70 ***************************** huh? after 60 yesterday afternoon
CYA 75 (I had projected 80 but ...)
CH 475-500 ************************* did the MA that brought the PH to 7.3 cause this?
Boric 50
Salt 3600

I'm careful with the water sample and the testing, and I took a second sample and got the same results. Is dropping the PH somehow upping the CH? And what do you think of the TA bounce? It happened last time I dropped the PH.

 

[Naplespool]

I'm bumping this in hopes that someone has an idea why my TA doesn't seem to want to hold 60 and why my CH seems to increase each time I drop PH to 7.2.

 

[pooldv]

A difference of 10 ppm on a TA test from one test to the next isn't a big deal and is within the margin of error of the test.

PH does not interfere with the CH test. CH is a little trickier test. I find that I need to make sure the reagents are shaken well and vigorous swirling is needed to get a good mix. This test benefits most from a speedstir for improved accuracy and ease of testing. But, again, you are close to the margin of error on the test and 450 or 475 is "close enough".

More detailed testing instructions here, Pool School - Extended Test Kit Directions

 

[Naplespool]

Thank you. I understand that +/- one drop is the margin of error, but it seems like I can make the TA stay down at 60 ppm. I will continue to monitor it. On the CH, a month ago is was consistently 400 ppm and I can't for the life of me figure out what might have caused it to increase.

On the CYA front, it seems that boosting it about 20 ppm to about 80 ppm CYA has had a significant effect on how much runtime/% I need on the SWCG, which I've been able to drop from 12 hours 55% to 35% and hold FC at around 9 ppm. That seems (3 day sample) to have reduced the rate of PH increase. And I've now got a $20 PH meter, that I'm comparing to the drops to improve my confidence reading PH around 8.0. I appreciate all the help.