refractometers

I' thinking about getting one of these but I'm apprehensive about it because I heard that for Fg reading they tend to be unreliable.

I batch sparge, all grain would this tool be a waste of money or would I benefit?

To check the gravity prior to fermentation, it's an excellent tool. I use mine with every batch (to get the OG as well as check other stages, at times). Once you get fermentation going, you'll need to adjust the readings (there's software/spreadsheets that will help you there) to get the correct reading from it. Personally, I use a hydrometer for the FG reading so it's a non-issue.

I have used it to get gravity readings on things like cyder, apple juice, as well as check the OG for my current batches of mead (the ones that don't exceed it's scale at least). With how small a sample you need for a refractometer, I think it's a very worthy tool addition. Plus, you don't need to worry about particulate fudging up the reading.

Get one with automatic temperature compensation, as well as both SG and brix scales and you'll be fine.

I got this one:

RSG-100ATC Black rubber strip Brix & Beer Sugar Wine Wort SG 0-32% Refractometer | eBay

Works just fine with a couple of exceptions. I absolutely don't trust the automatic temperature correction or compensation... whatever it is. I have taken measurements at reasonable temps slightly warmer than pitching temps, for example, and then wait a few minutes and get a slightly different reading. I don't think it's technique it just seems to work that way.

I use BeerSmith and the refractometer calculator on there for taking a final reading is spot on. Calibrated refractometer plus hydrometer reading and BeerSmith comes out exactly as measured.

It's not that they're unreliable for FG reading, it's just that you need that compensation calculation because you're no longer reading quantity of sugar in water, you're reading quantity of sugar in alcohol which has a different refractive quantity/quality.

I use a refractometer with the Beersmith Calculator during fermentation to give me idea of where I'm at. It's usually within a couple of points. The advantage over a hydrometer is that it only requires a small sample. I still take the reading at kegging time with a hydrometer.

+1 on the previous posters. I use my refractometer for pre-boil (mash and sparge), boil and post boil readings. It's easy to grab a few drops of wort and take a quick reading. Do I need to? Probably not, but I like to know where I'm at.

I use my hydrometer for anything post-pitch. By then, I want to taste, so I don't mind wasting the few ounces in the hydro tube.

Do you need one? No, I don't think so. Is it convenient? Yup.