alright! so today i made an up-flow algae scrubber!
found the jbj "nano-glo" refugium light at my lfs, and they have one of my tank on display there. i was able to test out the fitment, and come up with a way to place the light so that it shines into a chamber i don't have anything in. the water going into this chamber is flowing up through the chambers in the rear at this point, so i don't believe i will need any air bubbles to get algae growing here.
i bought this plastic mesh from my local fabric store, and cut it 3" to fit the width of the chamber front-to-back. mounted in this way i can shine the light on both sides of the mesh to get both sides growing. i notched it at the bottom so water can flow easily up both sides (it does not touch the bottom anyway). i also notched the top so that it hangs in place along the tank trim. i also did scuff up the plastic quite a bit so it is very rough.
here is how it hangs. this is centered in the chamber - not sure if it will stay that way on it's own or if i will have to fiddle with it.
this is the small jbj light. it has a magnet mount. the magnet mount on the inside of the tank will actually be in the return pump chamber next to this one.
this should line things up just like this, so that the mesh gets light on both sides.
BUT!
even as slim as the light is, it's still a tight fit between the tank and wall! too tight for me to be comfortable with leaving it due to it causing pressure points on the glass. so - guess next water change i will move the tank out a smidge.