This is the only fish store around that does exclusively salt water. The only other store that sells saltwater fish is Petco. I don't have much to work with being a newbie in this sort of thing.
I have gotten a magnesium suppliment as well as a calcium suppliment. I will soon start adding those into the tank. I will be doing a water change today to try and get my nitrates down. In order to keep what I want to keep in my tank, the salinity needs to be 1.023 - 1.025. Alkalinity needs to be 8-12.
I was told the algae (and I was not told this by the LFS) could have come about because of where the tank was in its cycle. I was told to turn the lights off for a day or two and I did. The algae is completely gone now.