I would, and do use a surface skimmer on my tank. The fluval surface skimmer was crap. Atman do a cheap Ehiem copy that I find works well.
I use JBL PhosEx to keep my phosphate levels down and would suggest something like that in your cannister. It works well for me.
Believe me, you need a skimmer. A cheap skimmer is better than no skimmer.
You need good lighting, even for mushrooms. If it is just a single tube then I would go with a PowerGlo tube and replace it every 6 months. If you add a second, a Marine Glo would be good.
My tank runs on powerheads, cannister filters, T5's and a 10 year old skimmer. The lights are new and the difference is amazing. Corals that were not growing are growing and those that were are growing even faster.