Any advantage to borates in high pH-tending salt pool?

[aholmes5]

I have a salt cell pool in Houston, TX. Our water supply is fairly alkaline here. On top of the alkaline water, the salt cell, of course, generates plenty of free base. I constantly add acid (~1 pint/week in a 15000 gallon aggregate plaster pool). In the summer, copious evaporation leads to the auto-fill running every couple of days. I have added an acid feeder to the pool which has stabilized my ever increasing pH and my scaling is now under control as well.

My question: Will borates give me any advantage in this environment? It seems like most of the users on this forum were constantly having a low pH problem, not a high pH problem.

Thanks!!!! This site is very cool - I'm on the BB method - just debating the third B.

Alex

 

[bobodaclown]

Hello and welcome to the forums. What's your TA level? Have you read about water balance for SWG?http://www.troublefreepool.com/pool-school/water_balance_saltwater_generator

I've just gotten my TA down to about 80 and the PH is climbing much slower.

Adding Borates will act like a buffer like TA does.

 

[chem geek]

The rise in pH does not come from the salt cell that "of course, generates plenty of free base". Though it is true that the addition of any hypochlorite source of chlorine including generation of chlorine in a salt cell has the pH rise, it is also true that the consumption/usage of chlorine is acidic and has the pH fall right back down again. This is described technically in this post.

The reason the pH rises over time is mostly due to carbon dioxide outgassing because the TA is too high and there is more aeration from the SWG running. There may also be some undissolved chlorine gas that escapes as well. As noted in the previous post, read Water Balance for SWGs to learn more. You first and foremost want to get your TA down, probably to 70 ppm, and you want your CYA to be up at around 80 ppm so that you can turn down your SWG on-time (i.e. you won't need to generate as much chlorine since less will be lost from sunlight). The Borates help both as a pH buffer and also as a mild algaecide so can reduce chlorine demand if your pool is "on the edge", though normally if you maintain the proper FC/CYA ratio as indicated in the Chlorine / CYA Chart, then chlorine alone will prevent algae growth where at a CYA of 80 ppm you want your FC to be no lower than 4 ppm.

 

[aholmes5]

Thanks so much for your reply! You guys are phenomenal on here.

My TA is 80. CYA is 80 too. My attached spillover spa has venturi nozzles on the four lower return jets that are connected to the main pump. It has an additional 8 upper jets that run on a separate pump. I'm wondering if the venturi nozzles are contributing to the outgassing since they are always aerating the spa. Would this also explain why my spa has more scale (in addition to the generally warmer water)? Would it be worthwhile to put a ball-valve on the air intake pipe and keep it generally closed except when using the spa? Sounds like the borates offer some benefit. I might hold off until my 2 year old is a bit older.

 

[Bama Rambler]

Stopping the aeration will help the pH rise some and so will bringing your TA down to about 70 or a little less. If you add Borates you can have your TA even lower than that.