Yes, I think your pump run time is not enough to help speed up the process. That being said, Aeration is not essential, and there isn't necessarily are requirement to lower the TA quicker. Overtime, as you add acid everytime PH raises to 7.8, lowering it to 7.2, the TA will eventually drop and come into range, and the PH will also stabilize when TA is lower. We usually recommend the "Lowering TA" process when the acid addition is frequent (daily) and annoying (SWG users). There is no requirement that it be done quickly - most users find by doing so you eliminate the risk of ph getting to high and causing scaling, which an happen rapidly in certain situations with good sources of aeration. The more bubbles, the faster the ph rise from aeration.
As for adding muratic acid - you want to pour it very slowly into the return flow of water, with the pump running. It's never a good idea to add any chemical with the pump off. It is not required that you add acid in the evening. I would do it at the start of the run time so that you get one full turnover of water to ensure it's adequately circulated.