The sticky waterbear posted above outlines the procedure for lowering TA, but I want to throw in my recent personal experience.
The likelihood is that you will not see any progress in two hours. The amount of time it takes to lower your TA is a function of many different variables:
1. The size/volume of your pool
2. How effective your aeration method is
3. How consistently you are lowering the PH in response to rises in PH as the TA comes down
I have been fighting a very high TA in my 24' AG (approx 13,500 gal) for the past few days. Last Wednesday (5 days ago), I took my initial reading of TA at 300ppm. I have been aerating by pointing my return eyeball up to cause a strong ripple effect on the surface of the water. The pump has been running 24/7 since then, and as of this morning I have a TA of 180ppm. During this entire process, I have been checkin my PH twice per day. Each time I checked it, the reading was over 8 (which is a sign that the aeration is working). After each test, I would use the pool calculator to calculate how much acid I needed to add to lower PH to 7.0, and add acid accordingly.
So in 5 days, I've managed to lower my TA from 300 to 180, and in the process consumed just over 2 gallons of muriatic acid. The most important thing I can recommend is to keep retesting your PH at least every 12 hours during aeration process. The more often you recorrect your PH down to 7.0, the faster the process will be. If you have to keep adding acid to keep the PH down, you know its working. Don’t expect to see instant results; it’s a long and tedious process.