Proper procedure for black tank rinse/sanitize

While waiting for the black tank to drain, I use the hot water from the water heater (keep it hot till then) into a home depot bucket. I then prop the flush handle open on the toilet and pour 4 gallons of hot water right down the toilet hole in about 6 seconds like a power flush. I do that twice then shut the flush handle and the black drain handle......then open the grey tank.