figure out how much drains back into it when power goes off then add an inch that will give you measurement from top to bottom for your 2 outer bubble trap baffles. for middle baffle make sure to leave 1 inch gap then measure as high as you want making sure to go over outer baffles ( I like to leave small gap on top also). for fuge baffle go slightly over your outer bubble trap baffle but not over height of middle baffle.
material depends what sump is made of. glass in glass is better due to better bond with silicone (can use acrylic but not as strong, more of wedged in with silicone than bonded) and you have to use acrylic with acrylic so you can weld on them in.