I recently installed a new Eheim ECCO canister filter. After a few weeks the water coming from the outlet was ssllloooowwww, so I took everything apart and cleaned it out, did not clean excessively because I did not want to strip the tank of any good bacteria it had aquired. But I did the cleaning and the water flow is back to normal, not to strong, but not super light like it was either. I purchased a pack of the charcoal to place in one of the five levels it has in the inside of the canister filter. Basically removing only one layer of the subtrate. I put the charcoal on the very bottom tier. Was that done correctly? And if I did it incorrectly (as if maybe should have been placed in the top tier). Will that have any effect on my fish? And also, will it give the water the crystal clear look I am going for? Thanks for the advice.