I'm trying to mimic the rainy season, so have lowered the water level and bumped up the temp a bit to start out.
When the pressure gets low here (whether it rains or not), I add 5 gallons of RO water, 10 degrees cooler than the tank's temperature and 'rain' it in with a spraybar.
Water here is wayyyyyyy hard, so I'm adjusting the GH slowly with each addition of water. When I do water changes, I do 50% RO and 50% tap.