When i first started i listened to a lfs sale's man pitch on purchasing 1in bio balls online to put in my canister fliter nad low and be hold they didn't fit. So now i just have them laying around underneath my tank collecting dust, i have 2 boxes never used, just opened to see if they would fit and how many i can get in the canister fliter which wasn't many at all, they go better in sump pumps i heard. I live in Mass, so if anyone is interested let me know. I beleave there 1in balls at a count of 74 in a box and go for about $7 online at dr foster smith. Make me an offer.