If you have to buy a cartridge filter every year one of 3 things is wrong:
1) Your cart is too small for your pump.
2) You are maintaining your cart incorrectly, or
3) Your situation is not good for carts, they are being destroyed despite correct sizing and maintenance and you should switch to sand or DE.
As much as I would dread having a cart, I am aware that the cartridges are not intended to be replaced every year and should not have to be.
Bookmarks