We have not used the official Litter Free Solution for over a year. We initially diluted antibacterial hand soap and used a small amount in most cycles. We do not refill the bottles as doing this destroyed one of our two units soap dispensing equipment. The box still works fine otherwise.
More recently we add a half-tablespoon of Lysol toilet bowl cleaner during each manual run of the cleaning cycles. This works great as Lysol seems to have been developed for such a use. It barely suds at all and I wonder if it could be diluted and used in one of the bottles.
To refill the bottles, we simply cut a small hole in the top and used a wine cork to plug the hole. We currently recommend pouring the solution into the box during manual cycles, so let us know if anyone tries something safe that works in the dispensing bottles.

