Unfortunately, converting from fresh to salt isn't cheap, unless you try and cut your costs with inferior or improper products. If you choose that route, you'll end up spending way more money when fish and inverts and corals start dying left and right. You'll have to get rid of your substrate and start new. Freshwater bacteria and saltwater bacteria are very different. The old substrate will cause a myriad of problems right from the start. You'll need to change out all media in your current filters with new and with your penguin, you'll need a new biowheel. You also have to start looking into water movement, powerheads, as well as the purchase of a good solid protein skimmer. Saltwater doesn't require a lot of mechanical filtration (i.e pengiun, or biowheels, or carbon) but you need a skimmer. Anyone is welcome to argue with that, but I'm sure you'll find more people on the side of the skimmer than not.
Live rock is your next step. For 29 gallons you'll probably want anywhere from 20-25 lbs of live rock. I've heard some say as much as a pound of live rock per gallon of water. Just depends on your budget and how much aquascape you want to do. You'll want to research "cured" versus "uncured" live rock. Cured live rock is rock that's been treated to kill off the necessary harmful bacteria and harmful parasites, etc. Uncured will result your tank cycling through a "die off" period, which will take longer. Some people choose to cycle their tank with uncured live rock rather than cycling with fish. Just do you research.
As far as your lighting goes, you'll be okay for most softies, zoes, some polyps but my guess is that SPS and LPS corals would require slightly more significant lighting. You'll have to check without someone who knows a little more about it. I currently run a 130 watt flourescent coralife setup on my 29 reef, but I only have soft corals, no hard coral.
You'll find as you start researching that you're going to investing a significant amount of money right from the start. Luckily you have the tank, which is usually the first hurdle to get over. Saltwater isn't cheap. Ever. You always want to research your choice of water. I usually recommend against tap water in all forms. I purchase RO water from my LFS, which they sell it at about 90 cents a gallon. IT's just easier until I purchase my own RO unit. Make sure you also have a marine test kit, and use it regularly. Saltwater organisms are WAY more sensitive to water changes than freshwater. Remember, the ocean is a big body of water, which means there are never large or significant changes in water chemistry. The goal of the Saltwater aquarist is to get AS CLOSE to those parameters as possible. Weekly water changes are key as well.
Skimmer, substrate, new filter media, powerheads, live rock. There's your first investment. After that, you'll find your wallet consumed by the actually stock of your tank...it'll take a hit, I promise. Not to scare you away or anything. But best of luck to you!
