I am 5 weeks into my cycle on a 75 gallon aquarium with a cascade 1500 canister filter. I have 5 tiger barbs, 2 coreys, 2 pleco's and 6 white clouds. I am testing with aquarium pharmaceuticals which is good testing kit. I have had zero nitrite, ammonia and nitrates since startup. I have bio-rings with coarse sponge on bottom (1st level) of filter compartment with regular filter pads on the levels 2 and 4 (uppermost) activated charcoal on the 3rd level. My fish are very healthy (great color and activity) so I assume the water is very good for them prior to a cycle. I will watch the ammonia and nitrite level and do necessary water changes when I get a reading. If anyone has any comments or suggestions why my cycle has taken this long I would really appreciate it. Also my tank is crystal clear now after a small battle brown algae.