I do not have a open top, it is a fold in have glass flat top. I am looking to upgrade my lights but because I have a glass top I need it to stick it underneath. Now the Fluval Aquasky is 100% water proof and is able to sit across the top of a open tank, but can also with the fittings be able to stick to the underside of the glass. However, this is the only one like this I can find. Anyone know any other automated lights that go under the glass rather than on top??