Seaclone says up to 100 gallon... I would say good up to about 60.. I run one on my 55 and I am collecting junk. I dont hear mine to much but then again I have 2 kids running around, tv loud enough to wake the dead, and a GF screamin in my other ear ( and that is on a slow day ) Anything bigger than a 60 get the most you can on what you can afford.
Like Dacia had asked depends of you are going Hang on Back or in Sump.
Prism and BAK PAK is a nice choice.
:happy: