tap water filter? replacing filter?

[tuck]

I have only used this filter. I have a 55ga reef and I change 5-10 ga of water every 1-2 weeks. I have never had any water related problems. I change the filter when the slight purple tinge in the filter media reaches the top of the filter. It lasts about 3 months depending on how much stuff it's removing from the tapwater and if your making water for extra water changes, cycling live rock, ect.