This +10. If you are trying to get something in the 300+ range a single canister just isn't enough. 2 Eheim 2262s would do it just at the limit imo. There are the cheap Chinese canisters that I can't remember the name of and 3 of the biggest version would be about the same price as one of the Eheims. Then again you still need the media/foam/floss to fill either one of those. My choice would be to turn that 75 into a sump but then it's plumbing/filter socks/media/pumps, while imo much better than the canisters, is still going to add up quickly. Alternatively you could look into corner matten filters which run on air, info on these are in a few threads on here and at Swiss Tropicals.
Heating is also quite often overlooked. Restocking either quantity or quality in a big tank because you used cheap heater/s that cooked your fish is hard to stomach. A quality controller plus a couple decent heaters can offer peace of mind.
I'm not trying to dissuade you, just trying to save you from the grief of improper planning causing headaches and further expense down the line. Plan it out, research everything that goes in a tank, then buy. I've made enough costly mistakes upgrading w/o proper planning. Your wallet will thank you later.
