Borates, Borate Testing, and TA ...

[madyogi]

I added borates to the pool last year but never measured the end result. I just did pool math to get to 30ppm then let that ride. We definitely liked the feel of the water, and my pH was rock solid most of the season, and I felt like we had fewer wasps bothering us for a drink from the pool. For all those reasons we are wanting to keep it up this year. We lost a fair amount of water over the winter closing and my arduous opening this year, so I added enough to bring up the overall level 10ppm, again without testing.

I have a few questions for the TFP community:

I still don't have any way to measure borate levels. I was going to get into the weeds with the drop test that has been described here, but it looked like that would cost ~$70 with the SpeedStir, plus it sucks up a few of the other reagents in my kit. Given that I don't currently have a SpeedStir, and getting an exact level on borates isn't necessary, I think I'll opt to just get the test strips and the SpeedStir for about $35 for now, and look at getting the other test chems at a later date. Is that reasonable?

Also, what is the relationship between TA and borates? My TA is now at about 60, which seems low to me from past years (I ran it at about 100 last year), but given that the instructions for adding borates explicitly says to adjust TA to the lower end of recommended level, I just left it where it was and added the borates (using borax and MA method). Those have been added now, and my pH is stabilized right around 7.6-7.8. Should I care about tweaking my TA? If so, what would be the indicators that I should consider raising it?

Thanks!

 

[JoyfulNoise]

You should really only need the mannitol and BTB indicator dye. The SpeedStir makes it easier but is not necessary. The mannitol powder can be scooped up with standard kitchen measures (its an artificial sweetener) so it’s not toxic. But if you don’t want the drop based test that is fine. You can use strips but they are hard to read and will give you a ballpark number. That’s also fine for borates as nothing bad happens below 100ppm. The strips will go bad easily so keep them sealed up, indoors in a cool dry place for max lifetime.

That increase in TA is minimal, about 5ppm or so. The warning to lower TA first arises from the fact that borates act as an additional pH buffer and pH buffers work both ways, up or down. So since it takes larger doses of acid to move the pH needle when borates are present, it’s easier to adjust TA first, then add the borates. But, in general, borates are not going to raise your TA very much; for that you should add bicarb.

 

[madyogi]

You should really only need the mannitol and BTB indicator dye. The SpeedStir makes it easier but is not necessary. The mannitol powder can be scooped up with standard kitchen measures (its an artificial sweetener) so it’s not toxic. But if you don’t want the drop based test that is fine. You can use strips but they are hard to read and will give you a ballpark number. That’s also fine for borates as nothing bad happens below 100ppm. The strips will go bad easily so keep them sealed up, indoors in a cool dry place for max lifetime.

That increase in TA is minimal, about 5ppm or so. The warning to lower TA first arises from the fact that borates act as an additional pH buffer and pH buffers work both ways, up or down. So since it takes larger doses of acid to move the pH needle when borates are present, it’s easier to adjust TA first, then add the borates. But, in general, borates are not going to raise your TA very much; for that you should add bicarb.

Good deal. That all confirms my thoughts ... So, my only last question is, should I even care about TA being on the low end of optimal if borates are in there? Is it generally understood that borates and TA work together, so when borates or present optimal TA is lower? I would normally add some bicarb just to adjust it up to 80-ish, but I'm not sure what difference, if any, it would make...

 

[JoyfulNoise]

Good deal. That all confirms my thoughts ... So, my only last question is, should I even care about TA being on the low end of optimal if borates are in there? Is it generally understood that borates and TA work together, so when borates or present optimal TA is lower? I would normally add some bicarb just to adjust it up to 80-ish, but I'm not sure what difference, if any, it would make...

Your optimal TA is whatever keeps your pH the most stable. Borates are part of TA, not separate from it. They are a high pH buffer that has higher buffering strength against pH rise. Bicarbonate alkalinity is the other component of TA that most people understand as being related to the addition of baking soda. Cyanurates (from the stabilizer you add to the water) also adds to your TA.

So simply monitor your pH. If it rises too fast, then you need to lower TA. If it falls over time, then you need to raise TA. If it’s mostly stable, then your TA is just fine.

 

[madyogi]

Thanks so much for the info Joyful! Just what I was looking for