A 10 gallon sump is way to small. I have a 125 gallon reef tank with a 55 gallon sump. Depending on what type of fish you want I would throw rock in the tank first & cycle it without fish. Like Tangs for instance need rock to swim in & out of & whole for them to hide in since they get scared & stressed easily. Plus with Tangs you want to wait a long time to put one in until your tank gets established. If your going to eventually do reef I would start with Instant Ocean Reef Crystals & also look into a RODI
system. If I new about that system before I used tap water I would of bought one from the get go, since I got brown diatom that was horrible! Good luck on your new hobby!