This is a bit of a ramble in no particular order.
the fans are only as effective as the air they're blowing over the surface, so you want to cool the room itself as well if possible: fans blowing air in/out of windows, opposing windows open so that there is a breeze through the house, pull blinds shut to block direct sun (although, these will still heat your room a fair bit if they're dark- if you want to get fancy, use spaceblankets). I've also seen mention of people placing icecubes or frozen bottles in their tank, which is easier, but the other stuff I mentioned will cool you as well
Water from the tap is much cooler, so doing water changes in the hottest hours will help. Mine drops to ~23 after a change and I've turned the heater off. No point having the heater rush back to 26 only to have the room bring it higher! If you want to change less water you could refrigerate it the day before, or just go the frozen bottle route. Your lighting may be emitting a lot of heat too, so you could turn that down, or move your photoperiod away from the hottest hours.
If you really get desperate you could try cover your tank
walls in a spaceblanket or something else that will insulate it
All I can think of for now!