Total Alkalinity Problem

[mkelley]

I've been able to keep my pool free of "pool store" chemicals for quite some time but now I'm kind of stumped.

While my pH is fine (7.6) my total alkalinity has kept rising until it's 175. The pool store says to add Muriatic acid, which I will do if there's no other advice here but I want to make sure this is the way to go (I'm not crazy about the dangers of this stuff but if it's the only alternative then I'll do it).

My other problem is calcium hardness and it's a two-edge sword because our city water is naturally hard so replacing pool water with it won't do me any good (I just got through replacing about 1/3 of my pool water to deal with other issues -- which it did but didn't affect this at all). I guess I'll have to live with it (it's about 475).

 

[JohnT]

Following your pool store's advice will get you nowhere. This Pool School article will tell you how to lower TA: http://www.troublefreepool.com/category/pool-school/lowering total alkalinity None of the conventional methods that pool stores will tell you to try will lower your TA permanently like this method.

You'll have to use muriatic acid, but it's not really a big deal if you just use a little caution. My TA is high (fill water is 480ppm), so I go through several gallons a season.

As to why your CH and TA rise, I don't know. What kind of pool, and what are the numbers in your fill water?

 

[mkelley]

I've never checked the fill water (probably a good idea) but I have an inground concrete pool with diamondbrite finish.

pH is always somewhat high (7.8 or so, so I'm always adding decreaser, at least once a week) but doesn't seem to be a huge deal. It's a pool/spa combo so I'm thinking the aeration that comes with the spa contributes to the higher pH (according to that posting you pointed me to). But I don't have calcium scaling and I don't have *rapid* pH increases (just a general slightly too high pH) so as per that article maybe I don't need to worry too much about the high alkalinity. (Make sure you actually have one of the above issues before lowering your TA).

 

[JasonLion]

You didn't say what your pool surface is or how old it is. If you have a plaster/pebble surface and it is less than one year old, the TA (and PH and CH) will slowly go up as the plaster cures. After one year and for other pool surfaces this does not apply.

 

[mkelley]

It's concrete with a "diamondbrite" finish (whatever the heck that is). It's three years old.

I did initially have high pH and had to constantly add decreaser, but it's slowly stabilized over the years to where I'm only lowering it once every two or three weeks. It's a given, though, that I'll need to keep lowering the pH.

For now I don't think I'll worry about the high alkalinity since I'm not experiencing the problems the article says it can cause. At some point I may try replacing some more water (due to the calcium as well as total solids problem I have) but first I'm going to have the city water tested to see just what I'm actually adding.