So I'm setting up a new 20 Long tank and I'm trying to make it as cheap as possible so I can spend more on the filter and stocking. I don't want to pay $21 for a glass top but I need something to go over it for the light to sit on. I have eggcrate I can use for a while but most lights are not suppose to go over open water and it makes me nervous. Suggestions on a CHEAP top?