Sick Goldfish

[Undercoverangel]

Hello all.  New to the group.  I have one large 7 year old fancy tail goldfish in a 20 gallon tank.  We upgraded  a few months ago to a bubble wall tank..  All was well until one day the tank started getting cloudy and green.  So we cleaned it and bought 2 snails to help with algae.  Since then it gets cloudy and murky within 3 days of any water change.  We removed the snails but that didn’t change the problem.  The water during the cloudy time tests normal.  We have tried everything we can to try and fix the problem.  Petsmart recommended a product to add but it hasn’t helped.  This did not happen with our last tank.  We have done total changes, new rocks, half changes…taken out all the faux plants and ornaments… so much work! The fish has been acting sick now since the last water change.  Not swimming much, not eating and hanging at the top and gulping. Though sometimes he seems somewhat normal.  He did have a floating problem a week ago from all the gulping but that seemed to clear up.  Any help or advice would be appreciated.  After spending soo much money we are at our wits end trying to keep a 69cent fish alive  🤦🏻‍♀️ his..or her name is Dinner 🙂 

[Colu]

Your tanks getting to much natural sun light or you have your lights for two long how long are you running your lights and is the tank near a window