Sorry about the cross post, but I need to make some decisions fast before I'm forced to buy more useless junk to keep my tanks going... I've hated Eheim and Fluval filters for years but events this weekend have brought this issue to a head for me (now this stuff is personal between me and Eheim), and have highlighted the need for immediate action. I've been trying for years to breed black banded sunfish. While gone for a couple of weeks and having my wife (who's not that into aquariums), the Eheim "Pro" (you need to be a "Pro" at getting these pieces of crap to work properly) filtering the tank just stopped working, again. Only a year old. I lost my best breeding pair and only saved the others by taking another POS Ehiem off of another established tank, doing a 50% water change and other emergency measures. These blackwater fish are particularly sensitive to ammonia and probably the fact that I was also running a backup large sponge filter in the tank may have saved some of them. While trying to get the top of the old filter off to fix it one more time, the handle broke. At this point I violently dissected the filter with the bottom of my boots. Gave me a look at just how these are put together, and what kind of a pathetic little pump they have driving this thing, one of their larger models. And I thought working with fish was supposed to be relaxing. Before anybody who's identity is somehow tied to product loyalty involving Chinese-made garbage, yes, I know more about these filters than the companies that import them do, do regular maintenance to clean their little impellers etc. But as the trite saying goes, garbage in, garbage out. German engineering my... So, I need to order some parts to start replacing all of my stock canisters, I can't trust them even if I wanted to, which I don't. I'm thinking that I can pair a Blueline (Iwaki design but much cheaper, made in the China unfortunately) with a prefab canister such as an Ocean Clear or Lifegard module. However, I need to figure out optimum pump size/canister size. I have everything from nano tanks (2.5 - 5 gallons) all the way up to 60 breeders. Even these Iwaki knockoff pumps are hideously expensive but there's no sense in overpowering the system and as an out of work conservation biologist I have to be careful about my remaining beans and tortillas money, . Does anybody know of general rules for optimum flow/optimum amount of medium? Is there something out there that grows more beneficial bacteria than Fluval media or any of the others commonly available?