Alkalinity and pH issues

[jseyfert3]

I have been frustrated trying to lower my pH because it has been so stubbornly high. Do I just need to keep banging away at it - will it eventually come down and stay down? Or will it always drift up and need attention?

In my experience eventually the pH rise will eventually slow almost to a stop, unless you are adding something with TA, such as water with a TA higher than your spa TA, or baking soda/pH up.

Also, if you don't already, you should shut all air valves when getting out of the spa so that the filter cycles don't apply needless aeration while the spa is not in use. Besides increasing pH rise, aeration also wastes a lot more energy.

 

[joecooler]

In my experience eventually the pH rise will eventually slow almost to a stop, unless you are adding something with TA, such as water with a TA higher than your spa TA, or baking soda/pH up.

Also, if you don't already, you should shut all air valves when getting out of the spa so that the filter cycles don't apply needless aeration while the spa is not in use. Besides increasing pH rise, aeration also wastes a lot more energy.

I don't have a circ pump so the spa uses one set of jets to circulate the water. The aerators on that are always off when I get out. The manual actually suggested leaving the aerator on the other set on. This set is run automatically, periodically, to keep the pumps primed or something. I leave that set on.

 

[joecooler]

So I am following your advice and working on getting the pH down ... it does seem to be dropping, it's holding under 8 (from 7.6-7.8) but does still want to creep up. Is the 7.6-7.8 range good enough, or should I try to get it to be stable at 7.6?

 

[ajw22]

Keeping in 7.6-7.8 is close enough. Don't drive yourself crazy trying to nail a number.

 

[Rattus Suffocatus]

Spas like to creep up in pH no matter what. There is a lot of water flow even when it's not being used, on filter cycles, heating, etc. When it's bubbly, then there is an extreme amount of CO2 removal compared to pools. I would be envious if I had your problem rather than 150 TA almost neutral pH fill water.

I use tablespoon at a time muriatic acid to bring it down and on a fresh fill the pH creep upwards doesn't stop until I get the TA below 70 or so, and even then... it just creeps up even more slowly. If your numbers are correct for CH and TA, then 7.6-7.8 is just about right.

But having pH creep up on a spa is normal...

I find that dry acid makes it harder to do TFP in a hot tub... so I do use Muriatic Acid... if you are concern about overdosing or harming the finish, then get a large 64 oz drink glass from a gas station and add a tsp or two at a time to a full glass and then dose that... it works fine....

The good news about these much smaller tubs of water is that if it gets too far out of whack it's easy to do a fresh fill ... so if you do something to spiral out of control ... start over....

 

[joecooler]

Where do you get muriatic acid?

 

[wireform]

MA is available in the big box stores paint department. They are available in 2 strengths. get the 34% one.