we use stress coat to dechorinate our water each waterchange. So, if that is your water conditioner just continue using it .
We now have 3 tanks without filters (also from filter probs). Waterchanges r done once a week. But we test the water every 2 days just to make sure the water parameters are ok and if need be do an extra waterchange. No airstones - when we did put them in the axies got skittish with the bubbles/waterflow, our pumps are too strong.
Are you changing your substrate, just that taking all your river rocks as well as filter may alter your water parameters quite alot, as some of the beneficial bacteria will be on the river rocks and filter media. Do you intend keeping your tank bare, or replacing with sand?
If replacing with sand, you cud do this by removing a section of river rock every few days and replace it with sand.