Congrats on the new system and for entering saltwater tanks!
I think that looks like a great start, though I have just a couple comments that I hope will be helpful
Make sure you get a good salinity tester, and calibrate it with home made standard solution, which is very easy, uses only common kitchen table salt and a decent kitchen scale or even measuring spoons:
https://www.reef2reef.com/ams/reef-aquarium-salinity-diy-calibration-standards.956/
Salinity is hugely important because when it's off, all your other parameters are off too
I'd skip the API Master Test kit, not because many here claim that it's terribly inaccurate (it's a little goofy, but mostly fine), but rather because you don't need half of it, which would be wasteful. You don't need to test for nitrite at all, it's not toxic in marine tanks, and a total non issue for reefing. Likewise, while pH has some significance, many successful reefers run at a chronically low pH of about 7.8 and they do just fine. Many successful reefers don't bother to test for pH at all. Unless you are growing corals professionally or competitively, you can safely skip testing pH.
I would purchase the Salifert brand test kit for ammonia, and either Salifert or a Hanna Checker for nitrate for when you're cycling your tank. Additionally, I'd get a test kit for Phosphate which is important for algae control and coral health; again Salifert and Hanna Checkers are solid choices.
If you're planning to keep some easy going soft corals you don't have to test too much, but it's helpful to know you're alkalinity at least. If you want to get into the more delicate corals you'll likely want to test for calcium too. Many here at R2R do not test magnesium at all as most home test kits are difficult to get an accurate result from:
https://www.reef2reef.com/threads/just-say-no-to-magnesium-testing-rmm-is-born.1017528/
So for test kits, I'd get ammonia and nitrate now, phosphate as soon as your cycle is over, and alk and possibly calc when you get into keeping corals.
Personally, I'd skip the Neo-Therm heater, I don't think they are worth even half the hype. I've had them fail in the "on" position (which is not uncommon for any heater brand), but if you do some searching you'll see that many of these heaters failed catastrophically. They would crack open and ooze nasty black epoxy into the tank, which killed everything and stuck to the tank and equipment in such a way that it could not be cleaned off, so all the gear was a waste. It would throw noxious fumes into the air that stained and damaged walls nearby. Oh but not to worry, Cobalt was more than happy to refund the $50 you spent on their heater
I'd also suggest a heater controller that will help prevent whatever heater(s) you go with from failing in the "on" position, and turning your tank into a seafood boil. The InkBirds are a popular choice, and are inexpensive at about $40 or so, which is great insurance for heater failures.
The TM Coral Pro salt is a very good salt mix indeed, but it's geared for those keeping tanks full of growing stoney corals, and may be more than you need at this time. You could get your tank going and cycled with inexpensive Instant Ocean Sea Salt, and then move to a more expensive, coral oriented salt mix later when you have corals actively growing in your tank, and if you find tat you need it. Many great tanks runoff basic, cheap Instant Ocean Sea Salt, but there would be nothing wrong with using the TM Coral Pro salt now if you don't mind the price tag.
And add one of these to your list of gear
Here's a recent thread discussing important gear that may be helpful:
https://www.reef2reef.com/threads/favorite-reefing-purchase-and-why.1156540/
I hope this helps and good luck with your new build! Don't forget to start a build thread so that others can follow along!
