I bought the 4 liter bottle of prime about 7 years ago. I don't know how much I have left, but I still haven't completely emptied into the smaller bottle, which I use for ease of dosing.The best part about Seachem Prime or the granular form Safe is, a little bit goes a long way. The initial purchase price tends to be a bit more, but if you read the label, the bottle (or jar of Safe) will treat a lot more gallons than the competition.