Doing a pool remodel and I'm considering switching out my current DE filter which uses the traditional rectangular grids to the quad. I read the owners manual and it states "You can expect an average cartridge life of 3 years under normal conditions". Wow. I still have the original grids in my 19 year old filter (acid washed twice). Considering that a 100 sf filter would cost $400 from what I've seen online for replacement cartridges, I don't see it being practical for me to switch if I have to replace the cartridges every 3-4 years.
For those of you that have owned a quad for many years, what has been your experience with how long the cartridges last before needing replacement?