Correct Alkalinity Range for Fiberglass Pool

[drips972]

I am very confused about what the correct TA range for my Viking Fiberglass Pool should be. The manufacturer's use and care manual (page 10) says, "The proper alkalinity is between 125 ppm and 150 ppm". However, I have always struggled with keeping my PH down to an acceptable level when the TA is this high, making it nearly impossible to balance the pool chemistry.

So this year, I decided to do some research, and nearly every website, blog, etc indicates that the TA should be 70-90+ (including the Trouble Free Pool blog). The lower TA range makes sense to me, since the PH needs to be between 7.4-7.6, and I have been pulling my hair out for years trying to balance it with the TA that high.

I would appreciate any suggestions regarding the correct TA level. Thank you in advance!

 

[Donldson]

Alkalinity doesn't have an effect on fiberglass, but low pH can. With the assumption that people will be using trichlor to chlorinate, which is extremely acidic, the higher TA range suggested is designed to keep those pools from developing acidic water. In the interest of not confusing people with multiple options, they just put the single suggested range in and call it a day. Though my opinion is that it actually increases the chance of harm to a pool not being chlorinated with trichlor as the constant need to reduce pH means that acid is being used often and while care is surely being taken accidents can happen and cause localized damage to the shell. A risk that is small, but spread out over hundreds of doses becomes almost inevitable.

You can allow your TA to go down, it won't hurt anything as long as you are monitoring and maintaining your pH appropriately.

 

[drips972]

With the assumption that people will be using trichlor to chlorinate, which is extremely acidic, the higher TA range suggested is designed to keep those pools from developing acidic water.

Thank you! This makes sense and is something I hadn't thought about. Now I feel more comfortable keeping my TA lower.