OKThe fungus treatment says to add a full packet to a 10 gal. tank. I didn't buy it because I have no idea how to mathematically determine how much to add in a 2.5 gal tank,
Whats the product? give me a link and I will try and work it out for you,
If the product says 10 gallon and it weighs 1 ounce then you use 1/4 of an ounce.
If its in pill form use a quarter of a pill.
If its a liquid get a syringe and draw up a quarter of the recommended ammount