Originally Posted by sallyjano
Is it empty? If so just get a one gallon container and see how many times you can fill it with water.
I took a 1 gallon betta tank that I had and I filled it up with water and filled the other tank up about 3 times. I phoned up the aquarium store to ask about the tank sizes and when I gave them the dimensions of my tank they told me it was 3.5 gallon and that Hagen no longer makes those ones because they have been replaced by the 2.5 gallon tanks. I asked him why and the man said he thinks because the 3.5 gallon was to close of size to the 5 gallon they sell and that is why they made it smaller. Also he thinks they did this so people can only choose between 2 smaller tanks rather than having 3 tanks that weren't much of a price difference. I don't know what to think but that sounds like Hagen, they want more people buying the 5 gallon because it's more money.