New to Saltwater tanks

hello, i have a 5.5g nano. i dont have a protein skimmer with mine. just 2 filters with nothing in them for current. all my filtration is with the live rock. u need a lb of live rock for every gallon in your tank if u do it that way. also you need a lb of live sand for every gallon as well. at least thats what i didn. with tanks these sizes a protein skimmer really isnt necessary as long as you have enough live rock. you'll need a good cleaner crew (snails crabs etc). in mine i have 2 turbo snail and 2 hermit crabs. also a coral banded shrimp (mind you those guys can be a little aggresive and territorial). for fish you'll prob only be able to get one. a smaller clown fish or maybe a fire fish. water changes are very important because salt water fish don't tolerate poor water conditions. you'll want to get a test kit. your ammonia, nitrite should always be 0. your nitrate should be kept below 20. i keep my nano at about 81-82 degrees. lots of info but if you decide to set one up they certainly are amazing!

ok, i guess you already know thats no good for 2 clowns, so theres no need to say that anymore. What we need to say is how to help the clowns.

for 2 clowns 30 gallons is best, although some members have 2 clowns in 20 gallons (you can count me in since thats what im planning too) 30 gallons is much easier to maintain and the clowns will be happier. By all means if you can get bigger than 30 gallons go for it. Learn more about them next time, please.

As for the first question, ok you have gotten the very complicated equipment stuff, well you dont need all of them. A UVS is not needed in any tanks unless there is an outbreak of a free swimming parasite or free swimming algae bloom. They are not needed for long-term use. You wont need one since you are a beginner too. Protein skimmer in a tank this small is not needed but it is highly recommended since it makes your life easier by lowering the nitrates a bit. Get a nano skimmer, ive heard very good reviews of the AquaC remora series nano protein skimmer, and very bad reviews of the fission nano skimmer. I would recommend getting one since there is barely any wrong from them (the only bad parts of protein skimming that i know of is that it can remove some good stuff like some stuff corals need but you can always add it back in easily). RO units are optional but RO water, to me anyway, is a must. An RO unit is where you can make your own RO water in your house, but you can always buy the water by the gallons at your lfs or walmart or something. So the decision to buy an RO unit is up to you. If you hear of ozonators, say no to them, they are similar to the UVS but are more expensive and are only used by the real enthusiasts with really really big tanks.

As for the filters you have, keep the hob and use it without carbon filtration as these arent used in saltwater much, this filter should be your main mechanical filter. Dont use the undergravel but keep the powerhead. Live rock or something similar should be your main bio-logical filter

Substrate should either be aragonite sand, or live sand. Dont use crushed coral as these trap fish poop and foul water, also if you sift it a bit it will release a cloud of dust no matter how well you rinsed it.

Good starter fish are damsels (highly agressive and shouldnt be in community tanks or reef tanks) although there personality has something to be wanted, they are very hardy and can survive through many minor mistakes that are almost inevitable. You can also look into gobies, blennies maybe, you dont have a large choice of fish to chose from in a tank this small, but dont think you cant have any fish.