So I went and checked out the light I listed and it it's not only small but dim - so very very dim. It looks like it's intended for a 2.5g cube (not sure what you keep in something that small). On the up-side though, while I was looking through the other fixtures I realized that the lid for my sump has a clear plastic section that is designed to fit perfectly with a Marineland led fixture. I also just happen to have one for my QT set up that I'd forgotten about (can't use it there as I have a coral in that tank atm).
Thanks for the replies - I think I've accidentally solved my problem - and for the first time in this hobby I did it cheaply!