Its small, but its not the end of the world. I'm no fuge expert but I recall reading a suggestion of having a minimum volume of about 10% of the system volume. Your fuge will be only about 5 quarts, about half the recommended size. My experience is that a small fuge is better than no fuge. I started off with a 4.5 gallon fuge on a system totaling about 85 gallons, about the same as what you'll have. I have a fairly light bio load but it worked for me. I've recently moved things around and improved my fuge to 5.5 gal which will have to be enough until I can build a custom sump that will give me 7.5 gal. Your fuge, like mine, is less than ideal, but it's not without benefit IMHO.