Raising Total Alkalinity without Raising pH

[castletonia]

I have 3 floor model spas that I maintain.  2 of them are fine but the most recent one I filled had high pH and low Total Alkalinity.  I have done some adjusting and the pH is currently 7.6 but in lowering the pH my Total Alkalinity has dropped to 50.

Is there anything I can add that will increase the Total Alkalinity without increasing the pH since Alkalinity increaser increases both?  I am using Di-Chlor in all my spas.  Water is city water with a calcium hardness of around 40-50ppm.

[chem geek]

If the pH in a spa tends to rise, then keep the TA lower and target a somewhat higher pH (say, 7.7).  If you are using Dichlor, then that is net acidic when accounting for chlorine usage/consumption.  You can minimize the pH rise not only by keeping the TA lower and target pH higher, but also minimizing the amount of aeration in the spa (i.e. spa jets).  If you want additional pH stability, consider adding 50 ppm Borates to the spa using boric acid (as in products such as Proteam Gentle Spa).

[castletonia]

Being that I am a ProTeam dealer, I have already added the Gentle Spa to the water.  Am I going to have any adverse affects from leaving the Total Alkalinity at 50?

[chem geek]

Just leave the low TA alone at 50 ppm.  There's nothing wrong with that, BUT if you plan to use Dichlor for chlorination then keep in mind that the TA will drop slowly over time so you'll need to add baking soda to raise it when that happens.  The pH may go down in which case you can target a somewhat higher TA if that happens.  Which way pH goes really depends on the aeration in the spa.