I’m one of those using tap water but I’m in Vancouver, Canada, where our TDS measures about 10. I just add Prime. No nuisance algae. I have a mixed reef as I like to collect whatever I think is cool, but I do have SPS. Nothing too crazy high end as I’m on a budget, but there’s a few nice ones. Actually I’ve had a few zoas melt away but haven’t ever lost an SPS or LPS.
I’ve just been in the hobby a little over 2 years. Didn’t know live rock from a baseball. I guess I’m “old school” in that I keep things pretty simple but I think not having tons of money to throw into a hobby played a big part. I used a hydrometer for the first year before buying a refractometer, but only because I dropped it & it didn’t look like super glue would fix it:p I just upgraded to a larger tank in Jan and had a sump for the first time. I don’t have ATO and just started manually dosing 2 months ago. I don’t mind as it’s something to do while pottering around the tank. I use Instant Ocean salt.
I guess being a newbie, I did so much reading about this hobby, and I think that sometimes we over-complicate/over-think things and are also too impatient. I’m amazed at how much expensive equipment is thrown at a tank build (read a lot of those threads, a great source of info) only to have a crash soon thereafter and re-build. Fancy equipment is not the recipe for success, imho. More important to research, learn from those who’ve been there/done that, and be patient.
Oh, and I was lucky to buy my live rock from someone leaving the hobby (he seemed sad but his wife was happy:p), who told me it was about 12 years old. Amazing rock. I firmly believe they are the secret sauce in my tank.