Keeping my tank clean

So I've got a 11" bullhead in a 55 gal. tank; I'm also using a large box filter with a single water intake spout. Unfortunately, it doesn't siphon out all the crap lying on the bottom on the other side of the tank. I don't have an undergravel filter either. Besides constant vacuuming, and occasionally spooking my fish, is there anyway of keeping the water particle free? I feed him pellets, but he always eats them all, so overfeeding isn't an issue. Some tips or tricks would be nice.

Add another large box filter or a canister.

If you get another fitler consier using an extension or make one for your lift tube so it reaches the bottom of the tank and has large holes to allow particles to enter. Or place a sponge filter over the lift tube as a prefilter.

put in a reverse under gravel filter

basically a power head that pushes water under the gravel creating a slight up current from the bottom, food, fish poo, etc stay in the water column until they are completely dissolved. Have a sponge or filter sock over the intake to catch debris.

it will cost u the price of a power head, or pump and about $10.00 in pvc fittings, and power to run it

drip systems and overflows can be a huge improvement if you are set up right

I feed him pellets, but he always eats them all, so overfeeding isn't an issue. Some tips or tricks would be nice.

Over feeding is most likely a big part of the problem. Bullheads have huge mouths and bellies and will gorge on all the food they can get. Then they produce copious amounts of waste.
One thing I learned trying to problem solve tank issues for customers when I worked in retail is that over feeding is the most common mistake.
Add more filtration by all means but also scale way back on feeding. I promise you can never feed a bullhead too little but you can easily overfeed one. It's a Win Win Win situation. Your tank will stay cleaner, you'll save money on food and the bullhead will live longer.

Thanks a lot you guys. I got a new filter and I'm feeding him less. Things are cleaner now.