ok so i have a fluval 306 on order for my tank and was looking at getting things ready for when the filter arrives. In the fluval manual it says make sure the distance from the top of water to bottom of filter is no more than 4.5 feet. My current setup is 5 feet will this cause me any problems or will it just reduce the flow rate a bit and i should i be ok? My water is 24" deep and the tank is raised fairly high up.

Also I was wondering what people are using in thier filter for planted fish tanks. From what i have read most people ditch the carbon and add some filter floss to the top bins but i was curious as to what others are doing.

It should just slow the flow, I would just set the filter on top of something to reduce the distance from the bottom of the filter to the top of the water.

Yea it should be fine, I think Fluval always says that. They say either too short, or too long, and they also say has to be below it (as most canisters are "gravity driven"). I just set up my Fluval G3 6 inches away from my tank which is not underneath it and it works.

As for what's in it, yes throw away the carbon and if there's extra room then put more biological filtration in there. Stuff like Fluval's G-Nodes or Eheim's ceramic balls are good. I also place a pre-filter on the intake so that can absorb most of the stuff and not clog the mechanical filtration of the canister filter (it's a lot easier to just clean the pre-filter than take apart the canister filter and clean that)

I'll have to measure when I get home in a few days, but I believe the distance from rim to filter is at least 5' on my primary tank. I have run Fluval 105 through 405's on that tank without issue.

ok good to know. Im also runing it though a diy reactor like rexes with the possiblity of adding bio balls to it to slow things down even more. but its only going int at 26g tank so a little slower flow is ok. I was thinking of getting some sort of spray bar for it to disperse the flow some as well.

Any suggestions about media set up? having never run a canister type before i see that there is so many options out there compared to the HOB style i currently have.