@ Sam: Yep tried there, they only have cloudy ammonia (home brand ) which doesn't have its ingredients but it bubbles up a lot when you shake it and I heard that means it has the cleaning chemicals in it which I understand are bad?
I have tried a few bulk places, Mitre 10 Mega, bunnings ect but to no avail, just wondered if any of the locals had a secret supply store.
@Ryan: My tank is 200L