I'm not saying this to "call you out" or anything, as I don't want to scare you off. You're new here, and frankly I'd rather you learn something and improve your husbandry than just think fish nerds on the net are complaining at you.
That being said, you almost definitely need to increase your filtration and water changes. I don't know what your WC schedule is like or what kind of filtration you run, but they should probably both be a lot more robust.
Stick an FX5 or Eheim 2262 on that thing and you'll be amazed at the difference. Canister go go go!
i would never do 75% but more like 3 25% (one a day for three days) thats a nice big tank to much might send them into shock hope this helps. as some one said post your filtration and that could help solve the green issue.
Put a UV sterilizer on there now. Post a pic of ur filtration and let the members help you adjust accordingly. There is no way your water should have color like that of any amount of time. Dont get upset when people start chiming in. Listen to them. Please post a pic of your filter.