I had JUST a penguin 350 on a 75G with 5 reds in it for a few months, and I agree I'd add more filtration (They did fine though). Dr. Foster and Smith's has AC110's for $33.99, and they are the best HOB I've used. If you just add an AC110 I think you would be fine.. Add a canister if you want SUPER overkill and not just overkill.