How often do I need to clean a cartridge filter?

If the filter pressure rises 8 to 10 pounds HIGHER than the pressure was when they were clean, then it is time to clean the filters. But it all depends upon bather load, debris in the pool (do you have a lot of bushes around the pool? Pine trees?), chemical usage, and (for a lot of our customers) if there are any dogs using the pool? One algae bloom will create the need to disassemble and hose down the cartridges so stay on top of the water chemistry (it is NOT difficult at all!). And if the dogs shed and are in the pool regularly it will create more frequent cleanings (shorter filter cycle) as compared to those who do not have dogs using the pool. Cartridge filters have gotten larger in recent years (larger filter capacity – more square footage of filter space in the “tank) so cleanings are less frequent than in years past. Assume it will need to be cleaned after the pool opening (after the water clears up), maybe once or twice over the summer, and then when the pool is winterized. But it all depends…