Still under 2% negative for the month, but still worth a note of caution.
I will still swear by the digital temp/salinity/SG meter. I got mine for $60 and it is the most efficient and time-saving test that I have ever picked up for reef-caretaking. Just test it in the solution before you use and make sure it is reading correctly. Then tests all of your tanks in one swoop. I have five tanks, a lr holding, and checking all of those with a refractometer will take me thirty minutes when you include testing the refill water when I do a change, cleaning it off after every use, dropping the water on, flipping the lid, looking in, focussing, opening washing it off and repeat 6 times. Let's say two tanks were a little off...that means adding and retesting until you get it on point...
With my digital meter, I get it correct, on point, and do this for all my tanks within five minutes!! Dip, check, out and on to the next one; repeat six times. Hit a button and make sure the salinity and SG are a match. Hit the same button and check your temps and make sure your thermometers are correct. With this meter, I don't only test SG, like a refractometer.
I will say this: a refractometer IS much better than a hydrometer, which are very "iffy" at best.
www.marinedepot.com has the same type of meter I got for something like $90, but I'm sure you could find it cheaper.
