Evening, was wondering on the ReefMat sizing if I should go by GPH or tank Gallon size or both they have listed. Dilemma is I’d like to go with the 250 model which is rated for 900 GPH since the physical size is smaller however my tank is over the 66 gallons, Opus 300 is 69g with 14g sump. However the GPH is only 525. Would I be ok with the 250 or should I go with the 500? Thanks much!