personally i would beef up that stand a bit on the vertical corner legs , 2 x 4 on the corners will tend to tip without a " L" made from using 2 , i know its not a huge tank but one little bump to the left or right and your whole system can end up on the floor once the weight ****s to one side.
better safe than sorry for the cost of a couple 2 x 4"s
cheers
denny