, a Remora is way too small of a skimmer for a 90. They rate them up to a 120, but I would cut that in half. If you have room in the sump, I would suggest an Octopus skimmer and that will cost less than $200.
For macro in the sump I use chaeto, but if you keep a lite on the fuge all the time you can use caulerpa. I just use a pc
spotlight from HD to light the fuge.