Let's talk water flow, a/k/a "turnover." The general idea is to turn the volume of water in your tank over 10 to 20 times per hour. Since you have a 55 gallon tank, that's 550 to 1,100 gallons per hour (GPH). I doubt the pump on your sump is doing enough, so let's measure it. Instead of counting feet of head, identifying your pump and finding a chart for your pump on the internet, just collect one gallon of water as it drains from your display tank to your sump. If it takes 1 minute, you got 1 gallon per minute or 60 gallons per hour. If 10 seconds, then 6 gpm or 360 gph.
Let's assume your sump pump ain't cuttin' it. There are four solutions: 1) add a fan, 2) add a closed loop, 3) replace the pump with a stronger one, or 4) reduce the number of turns in the pipes. Forget #3 and #4.
#1 is easiest because there are a kajillion fans on the market. Just buy one and mount it inside the tank. It'll move water around at a rate of so and so many gallons per hour. There are oscillating fans, wavemaking fans, and choices out the wazoo. I like the Koralia series, but shop around and pick whatever tickles your fancy.
#2 is the hardest. A "closed loop" is a loop of pipes with no opening to air. You buy an external pump and a bunch of PVC or flexible tubing. You rig it so water is sucked out of the tank underneath the surface and pumped right back into the tank under the surface. No bubbles. It creates water flow. You can get very elaborate with alternating currents, SCWDs, wavemakers, etc. Some folks don't bother with a sump at all, using only a closed loop. I use both. See my thread "Plumbing redesign blog" for detailed photos and explanations for how I made mine without drilling any new holes in my tank.
Also, look for dead spots where there is no water current. With any good luck, you'll be able to find it as the place that is consistently dirtier than the rest of the tank. If you find one, move a rock, aim a fan at it or whatever.
Have fun and Let's see some photos. (Be sure to resize them to 550 by 440 pixels.)
PS- Find a convenient schedule by which to do water changes and stick to it. I do 10% changes every week. By that I mean I discard 10% of the total water volume and replace it. Your system has 60 gallons, so that's only 6 gallons. (I do 25-30 gallons per week.) If you used tap water and got a diatom bloom, then buy an RO filter. The salt you buy to make your saltwater is scientifically diddled to make sure that your regular water changes add all the stuff you need to have in your water. You need not add anything else whatsoever until you've been at this for a lot longer. After another 6 weeks, things will start to settle down and then you can start fiddling.
