I just purchased and installed my new Rena XP4 on my 55 gallon FW tank. WOW this filter amazing. My tank went from,.. What I thought was clear to crystal clear water which now has a slight blue ting of color. Anyway the book indicates to do maintenance on the canister every 4 weeks. What are your thoughts. In addition I use Sachem Matrix for Bio-support. Do I change this OR simply rinse the Matrix & bio-stars with my tank water. Thank you.