RocketDaryl; I vote for, near 5 gallon versus a tad over 6 gallon tank. The length of the Standard and the tank of the R3T appear the same. The height, of the Standard's tank, however is shirley of a greater capacity than the difference of the suggested 5.9 of the R3T and the 6.4 capacity of the Standard's tank. I vote, near 1.5 gallon less than the Standard. I can't speak to the width differences.