Heat and light are not going to do anything. Garlic helps, but is not a cure. I'd QT, as that will cost less than potentially losing $100+ in fish and without that, the Ich is always going to be in the tank.
It was already discussed in another of your threads, but putting fish in a tank that is smaller than suggested usually causes stress. Putting two dwarfs in that small a tank will cause stress (due to aggressiveness towards one another and not enough space to be comfortable in). Stress makes fish weak, which makes them more susceptible to picking up common problems like Ich.