So I have been wanting to get back into the hobby for awhile now, here is my story.. I was gifted a 72gf Bowfront tank and stand awhile back. I was running a fresh water set up for a while, and had roughly about 7 goldfish including a Koi. All was going well with my tank for roughly 3 yrs, than something started to turn. My fish started to die off. I was so upset that I felt I could never have any fish anymore because I didn't want to put another fish through the misery. There the tank sat for nearly a year with the old water gravel. I didn't remove the water and the filters weren't running or anything or anything... Bad idea I know. But here I am trying to change all that and get started once again. There was a fungus type mold looking thing coating the top of the water and a cotton type fungus on the gravel and glass. I purchased a brand new scrubber and razor to clean the glass as well as a Python No Spill siphon off amazon. I emptied the tank as much as I could with the siphon, which was about half and inch of water just under the gravel bed. I tossed nearly 50% of the gravel exposing some of the old food and waste that has been sitting in the bottom, used a net to get rid of the fungus that coated the water and filled the tank. I rinsed out the 2 Aquaclear 110's media and had it running for several days. The water is now cloudly but atleast the mold and algae is all gone. There is also a foam build up at the top of the water. What I really want to do is get back into the hobby and turn my tank into a salt water aquarium. I've seen a bunch of videos on set ups and how to care for it and been looking for nearly a year to get started. But now I am kind of stuck, what can I do with the tank to get it clear again. Starting over is really what I want. I need the tank to look new again without any defections before I start. How can I get the tank clear and remove the foam or impurities. I am not in any means in a rush to start, I know it will take time, but I also do not want to invest the money in a new filter since I want to be able to buy a sump and overflow box and all the bells in whistles to get this running right. I am afraid if I get these items now, the tank water will just spread whatever it has to the new units and the headaches will spread to two tanks instead of one. What do I do? Sorry for the novel, but I don't know where else to turn... Thank you in advance.