So I decided to test the water and added a dummy fish, swam around happily for about an hour or 2 and then slowly stopped swimming and more or less started drifting :dead%fish . Might need to drain the tank and refill? (could be the resin leaching chemicals? sand?) I've added some carbon for now incase it is chemicals so I can start removing them. Only other thing I added was "sera" crystal to help filter out the cloudyness, could that be the problem?