Procedures for Lowering TA
There is also the acid column or slug method myth that was discredited in
this paper. It's not that the method doesn't work at all, since the amount of TA lowering is solely dependent on the amount of acid you add and not how you add it, but rather that it is not the safest method (pooling acid in one area can damage plaster/vinyl surfaces) nor the most efficient (it can take longer for the pH to recover in time for you to add more acid to lower the TA some more). The efficient procedure for lowering TA (especially lowering the TA a lot) is described in
this post and in the Pool School
Lower Total Alkalinity procedure. The procedure works because the outgassing of carbon dioxide is accelerated at lower pH as shown in
this chart.
The handbook only says to add acid to lower the TA and does not discuss more efficient ways of lowering it via lowering the pH and increasing aeration (along with the acid addition).