I'm not even sure if the guy who "tested" my water actually stayed with the test because it was crowded one guy took my water to be sampled another one brought it back with a paper approx 15 mins later then yried selling me some live bacteria... In a PANIC rushing home I stop at the nearest pet store and had it retested the ammonia reading wasn't that high but a tidbit off I put in the ULTRA CLEAR saltwater bacteria now I'm in route to a more reputable LPs now to have water retested and purchase a testing kit... Will post test results shortly
If you aren't already going to a dedicated saltwater store rather than a "pet store" or even a "fish store". Those test strips aren't particularly accurate. The SeaChem Ammonia Alert badges are about the same cost, and they last a year. They change colors with the ammonia level in the tank. I don't find the actual reading on the badges is very accurate, but it does accurately alert you to the presence of ammonia in the water. SeaChem Prime is compatible with the Ammonia Alert, as is the API Ammonia test kit. Most test kits are NOT compatible with Prime, and will give you a false ammonia reading where there is no toxic ammonia present. I'd suggest you get some Prime and an Ammonia Alert. Keep the alert in the tank, and dose the Prime when needed. If there are fish in there now, as there is, Prime needs to be dosed until there is no toxic ammonia detected on the Alert. Keep in mind that when you dose the Prime it may take up to 4 hours for the color to change back to "zero", but when ammonia is detect it is almost instantaneous color change.
Nirite is not toxic in saltwater aquariums like it is in freshwater aquariums, so don't even bother with a test kit. For nitrate, I suggest the Salifert test kit. It will cost more than you are used to paying for a test kit, but it is much better quality and it's a test kit you will use often. There is nothing worse than getting inaccurate test results and messing up your tank when everything was just fine.
For a fish only tank, you will just need the nitrate kit. If you want to have fish and soft corals then you should get the Salifert Nitrate and Alkalinity kits. If you want LPS or maybe even SPS corals too then you'll need the Salifert Calcium, Alkalinity, Magnesium, Nitrate, and Phosphate kits as well. You can buy them as you go. Salifert is a really good brand of kit to buy across the spectrum. There are others, but these are the cheapest ones I recommend.
I do not recommend the API Master test kit. They do not have expiry dates, and you have no way of knowing how old they are. It's also easy to forget when you start using them, so they can get very old and inaccurate without you being aware. I also find that several of their tests are not reliably accurate even from day 1. Their ammonia and nitrate kits are an exception. I write the date I open them on the package and throw them out when they are 1 year from opening. I don't use them anymore though, I use the Ammonia Alert and the Salifert Nitrate now as I've had more reliable testing.