Pool Math conflict

[WASP]

I have been using the Pool Math online application on my iPad for quite some time. Very helpful in understanding the chemistry relationships.

This morning the app recommended (in the pink section) that I add 97 oz of MA to drop pH from 8.2 to 7.6.

At the bottom of the app (Effects of adding chemicals) it says that 97 oz of MA will drop pH 1.3. That is twice the drop shown in the pink section of the app.

Please help me understand the conflicting values.

Thanks for the crystal clear water in my pool.

 

[jblizzle]

The top takes your actual TA level into account. The bottom does not and makes general assumptions. There is a note by the effects of adding chemicals that says it should not be used for large pH adjustments.

Trust the top.

 

[WASP]

Thanks for the clarification.

I was confused by the conflicting values.

 

[ewkearns]

I would suggest, when making large adjustments, to put in half the predicted amount and re-test. It is better to "sneak up" on the goal rather than to overshoot it.