reason why i ask this question is because i have plans for a 250-3oo gl tank for my aro and i have another 100 gallon tank i plan to use for an aquatic lizard.I don't want to buy another 404 filter and plan on using the fx5 for the hundred gallon that is currently in use.
no a FX5 should do just fine on a 100gal i have one on my 125 along with two penguin 350Bs and I also have a FX5 on my 75gal. and they work out quite nice