I have 2 coreless filters in my Bullfrog A7. The touchscreen and app prompts me to "Rinse filter with hose" every 30 days and "Clean filter in solution" every 60 days. My water is crystal clear and needs nothing except for 150mL chlorine after each soak (every 3 days) and ~40g dry acid every 2-3 weeks.
Usage is 2 persons, 3 times a week, 2 hours per soak = 12 person-hours per week. Filtration+ozonation set to 0.5 hours once every day, and filtration+ozonation also runs during heating cycles (which is 3-6 hours before soak time).
The higher your person-hours of usage per week, the more frequent you will need to clean your filters. It also depends on the filter capacity, in terms of how much dirt it can hold before it either clogs or starts releasing it back into the water.
I use the Mikise PowerPic Reach (
MIKISE | POWER PIC REACH | Ultimate Filter Cleaning Tools) first to blast the dirt from the inside out.
Then I use the Mikise Filter Flosser (
MIKISE | FILTER FLOSSER | Ultimate Filter Cleaning Tools) to spray the filter from the top of the pleats down through bottom. Other similar filter tools are plastic instead of metal, with plastic prongs that stick in between the pleats. These deeper prongs may or may not work better, I haven't tried.
These 2 Mikise tools are all metal and built very well, expecting them to last 10-20 years if not more. The plastic tools seemed like they would have a short life and not survive an accidental drop, so I didn't bother trying based on their plastic construction.
After pressure washing with these 2 Mikise tools, I soak the 2 filters in their own buckets that are small enough such that the filters sit in the buckets with minimal space to spare on the top and edges. I then add filter cleaning solution according to the bottle's dlution ratio, spin the filters around so the solution is thoroughly mixed, set a filled glass jar on top to keep the filters submerged, then leave them overnight. Next day, rinse the filters thoroughly, and reinstall while wet.
Some people recommend drying the filters before reinstallation, but no one has provided me any real logic or science behind it, or even a spa manufacturer or filter manufacturer recommendation. Unless the filters are brand new on the store shelf, filters are always wet no matter what, whether they are in the spa, being rinsed, or being soaked in solution. When other paper media gets wet and dries, its fiber structure deteriorates due to microfolds and microcreases developing inside the media as it dries, and the paper also shrinks and pulls away from glued/bound edges. Can't say if the spa filter media reacts the same, but we do know that these filters in their natural state are completely wet and immersed for weeks/months at a time, so I don't see any reason to change that.