I've used both, ocean clear and the rainbow double mechanical unit and they both are great filters depend how you set them up, the rainbow have a 5 microm compare to 25 of the ocean clear so it will trap more particules and will clog faster, what you need its a spare microm so when service just swap them, clean the dirty one with clorine and water for next time service, they last for many years so you don't have to keep buying cartiges. Personally i prefer the ocean clear, easy to work, there is a drain valve when you need to empty the canister for service, also you can use a bag of carbon or any thing you like in the core of the microm, not on the rainbow.