jb1 has you on the right track. I switched my tank from cc to live sand a couple years ago. I just used one of the substrait "vacuums" to pick up all the cc. I did clean it real well first to get rid of as much detritus as I could so my water wouldn't be a total mess. While I had cc, I used to vacuum it about once a month. It's time-consuming but you should have seen all the gunk that I got out of there.
First things first, though. What did you add to your tank in your attempt to kill the ick? If you used anything with copper in it, it could be deadly to your livestock. Also, have any of your left-over fish exhibited any symptoms of ick lately?
Normal output (NO) flourescent bulbs are usually good for about 6 months before they need to be replaced. If the bulbs you have are over your tank are 40 watt they are NO bulbs.
If you decide to switch to a sand base, I'd use some live sand and supplement that with Southdown. A live sand bed will grow bacteria that converts ammonia to nitrate and nitrate to nitrite.....which gets exports out of the water column, generally, through water movement at the top of the tank.
Jim