I only use about a cup and a half of GFO monthly for my 250 gallon total volume. I also buy the ebay GFO for about $220/25 lbs. Works just as well as the BRS stuff for me... probably use the same supplier.How much gfo do you go through? Just realized for a 300g tank brs recommends 6 cups 4-8 weeks that's
15-30$ a month :O