New reef tank! 41 Gallon Fluval Osaka. Suggestions?

[redearslider]

Hi everyone!
I am Tasha and am starting a reef tank.

It is a Fluval Osaka 41G

I have in it so far:

30lbs argonite
50lbs live rock (Some is lava?)
2 powerheads, (1 small and one large)
A small fluval internal filter.
A Current USA SunPod 250W MH Fixture
5 hermit crabs
2 pink turbo snails

I also added some green zoos and green star polyps

All of my levels are now good and at zero, but I just got a bunch of brown algae all over my rock, pumps, and sand! it looks terrible, I am thinking this is a normal process though?

Anyways I know I will need to add more things soon, and figure out something for a skimmer/filter. and stocking help too

I am fairly new and have been doing a lot of research but any suggestions would be greatly appreciated! Thanks