Be careful, I've seen a conversion chart floating around in google search results that's way, way off. This website is a bit archaic but EXTREMELY handy for everything salinity. There's many more salinity calculators for any imaginable situation.
https://www.hamzasreef.com/Contents/Calculators/SalinityCorrection.php Weighing your salt and precisely measuring water makes the whole process nearly flawless. TM has a water impurity of about 2.5 and Instant ocean 5. The hydrometer and calculators are great for fine tuning your new saltwater and reef. I made a handy chart to tape on the box showing what the hydrometer should read for every temp assuming you start with 1.0264sg water at 25c/77f
The BRS best of test kit series was an absolute joke. They've done a lot for the hobby but recently it's all about sales. With multiple reefs and maintenance accounts I burn through about 5X as many kits as the average user. I've tested multiple kits/refills of every kit pictured and compared results to a few icp tests. The only one I'd say is plain ol bad is the red sea magnesium. It's very imprecise. hanna colorimeters are nice if you're colorblind or hard at seeing but otherwise WAY overrated by their #1 salesman. Hanna phosphate is extremely tedious and the hanna alk reagent drifts within 45 days of opening. Also many bad batches reading 1-2dkh off. Salifert alk is actually faster and more precise if you know how to use it. Red sea pro phosphate fantastic accuracy and precision; especially at ultra low levels under 0.08. If you have a decent set of eyes you can detect po4 under 0.01 yet still above dead nuts 0.00. I call it 0.005. same for their nitrate test below 0.25- I call it 0.125ppm. Nothing else too egregious about the rest of the kits; The TM kit requires EXCELLENT eyesight so I wouldn't recommend it though it is very precise and accuarate. The nyos nitrate is expensive, doesn't measure well in low ranges and the dropper bottles were horrible in 2/3 kits. The red sea calcium kit leaves a precipitate that needs acid washed after every test and the color change-back is annoying. It can change back and require another drop for up to 20 seconds after turning blue.
I narrowed my kits down to a nice little compact tray to hold the tests I trust most. I'll periodically buy a new kit to try out and verify but I've pretty much set in stone, the kits I'll trust the rest of my life. Salifert for Cal, Alk and Mag. red sea pro(algae control kit) nitrate and phosphate. I gave away my refractometer and bought a second TM hydrometer for backup. I also started using the Salifert Potassium test. It's expensive, the sample size is smaller than I'd like and it leaves a very nasty precipitate. I started doing double test volumes and use a mag stirrer for higher precision. I've almost used up my first kit and established a reliable trend after switching salts- I was at 410ppm and dropped to a pretty consistent 370. I sent an icp test out and it came back 375. I started dosing potassium and watched it rise accordingly with what I dosed. I just got my second kit yesterday so I'll be able to give it my stamp of approval in a bit.
