I have the same Black Diamond bag marked 30-60 40-80 in my 10g. I believe it is 40-80, it is very fine, finer than pool filter sand which I have in my 40b. it takes A LOT OF CLEANING, I did about 1/4 of the bag at a time in a 5 gallon bucket, it took about 2 1/2 hours to do the whole bag. when the sand was clean I moved it to another bucket, repeated with another 1/4 of the bag. a lot of work but looks great.
I have a Crowntail Betta in the 10.