Hi and welcome!
First off, your lights are not strong enough to sustain any corals, even the low light ones. 110 watts of lighting over a 125 gallon tank is not even 1 watt per gallon. You should aim for at least 4 watts per gallon, and that is just for the corals with the lowest lighting needs (zoanthids, mushrooms and softies). If you want to keep LPS corals, you should aim for more than that, while clams and SPS require even more. Anemones need the most, and usually need around 8 or 9 watts per gallon at least.
Next, your nitrates are high. Understandable for a fish only tank. Fish can tolerate high nitrates, but corals and inverts can't. 30 is in the area where they will start to harm your inverts. For corals, you need to keep nitrates as close to zero as possible, but under 20 is okay.
In order to keep corals, you will first need to upgrade lights. If yours is a standard sized 125 gallon tank, you could go with either T5s or metal halides. In the meantime, you will need to work on improving your water quality -- do regular water changes of 10 to 20% weekly of RODI water -- not tap water, which can lead to major algae problems and can contain things that will harm your animals. If your nitrates don't come down, up the amount or the frequency.
Certain types of equipment will lead to high nitrates also. Penguin filters tend to do this unless the media inside of them is cleaned very thoroughly once a week or once every other week. Same with canister filters and wet/dry filters. If you are wanting a reef tank, I'd get rid of the Penguins and buy a better protein skimmer. If you have 1 to 2 lbs of live rock per gallon and a good skimmer, that will take care of your filtration.
Also, you do not need to be adding calcium and essential elements. That's just wasting your money right now. For easy corals (like the button polyps you picked up), they will get any elements they need from your salt mix. They also do not have strict calcium requirements. You shouldn't be adding anything like that unless you have tested your water first and determined a deficiency (which I doubt you have).