Hi I started with a 55 gallon and used the eheim wet/dry, and the eheim canister. I will be the first to tell you that I had a great deal of algae covering the sand glass, LR, and pretty much anything but the fish. Had to clean the tank daily. Since then I have upgraded to a 140, and at first I had the same problem. It didn't go away until I built a sump with a refugium. Do some research on them, refugiums are great especially for tangs, and though it is ideal to have it in the sump they can be put into the DT in a corner or in the back, basically wherever you can hide it. Refugiums give a place to grow Macroalgae which will not only help to keep nuissance algae out of your DT but they also improve your water quality by a lot, lower Nitrates significantly. Since Ive put one in I have to clean the algae off the glass maybe once a week, before at least once a day.
Besides a refugium, which IMO is the best way to go, and the cheapest b/c you can build it yourself. but a UV sterilizer also helps to remove the green feel free to ask questions but try a fuge you'll love it also nice spot to put small fish, seahorses, or anything that cant go into your DT b/c of threats