...but have a doomed myself here by purchasing a 30 gallon tank?...
Wow.
I had the same 55 gallon tank for 24 years with numerous, upon numerous changes, etc.
I also got a Nano a while back. I think nano's are awesome. The problem is not that a 30 gallon is a very small tank. Even a very large 300 gallon tank, is so small against the ocean. Smaller tanks can have their tank parms change very fast.
In the past, the going saying was "start with a larger tank" that can stay more stabilized. However, with so much info on the Web with MR forums, etc. I have learned much more in the last few years, than the many, many years, before.
So real advice, in my opinion, is to keep the tank, and do lots of research. Also, remember, animals do not like change. Sometimes, even a tank with bad parms, will do okay, because the fish got used to it. So even correcting a problem, sometimes works better, when going slowly.
So bottom line, is just to do research, do small changes to parms at one time and always look for ways to reduce fish stress. Like keeping a small bio load ( not a lot of fish in tank), as this can increase phosphates and lead you to have additional problems that will have you seek out more equipment to buy.
Just recently, I saw a large tank, with very little equipment. Seems, my little Solana had much more equipment than this tank. Both tanks do well. However, I enjoy "simpler is better"
PS. If you think your tank is small, you should go on to Nano Reef and check out Pico tanks. These tanks are even smaller than nano sized. I have seen amazing Nano tanks and Pico Tanks.
PSS. As you can guess, I think I want to try one of these Pico tanks.
What's interesting, is how a lot of people always want bigger tanks. I never did. I think my 55 is large enough. However, I do like new equipment, so buying a new setup is always fun. However, as you can see, I like to go on the smaller side. To each their own.
I find AIO ( All In One ) tanks, very cool, with their own advantages and disadvantages.