How big are your Rays because an fx-5 in all aspects isn't enough for 2 good size rays. Not to be rude I'm just going off personal experience. You would need more overall turnover and more bio and mech filtration. I have an fx-5 on a 110 gal and it's not exactly what if consider up to my standards. But don't get me wrong it's a good canister filter.My fx5 does well in my 200 with 2 rays and tiger pike and payara water change twice a week
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