Gentlemen... a milliliter is one thousand of a liter ! So that 947ml bottle is almost a liter and the next one up is a gallon or 4x as much. Think next one up is a 5 gallon pail and that one is a bit of an exaggeration for our needs . Lija, I get them by liter bottle; but my source is 5 min. drive away. If planning to build more tanks or redo others, that gallon bottle might be the way to go. Good luck !