I am using an ATC Refractometer that I got off ebay for about $30 last winter. When I got it, I calibrated it (with my tap water) and things seemed to be working fine. I know you are "supposed" to calibrate with RO water, but I figure that since I brew with my tap water, then I should calibrate with my tap water since my tap water is what I want to consider "0".
Anyway.... My last few batches have been coming up short on OG and I had been chalking it up to me still being on the learning curve with my new system.
However, when cleaning up after a brew session Sunday night I happened to look through the refractometer with just tap water on it and found that it was reading BELOW 0 Brix. There's no scale below zero, but I estimate that it was at about -1.3 Brix.
Thinking that my calibration was simply off, I took the thing into the house with me and started typing an email to a friend who had also used it that night to let him know that the thing was reading badly.
I looked through it again to make sure it was really off by -1.3 so I could give him a better idea about how badly it was off , but the thing was reading apprixiately -0.2... same water that I had just saw reading -1.3... All I did was carry it into the house from the garage. WTF?
So, I took it back out to the garage and sat it on the workbench for about 10 minutes and looked through it again. Back at -1.3.
Thinking back when I got it, it was winter and the house would have been at about 68*F. That was the temp it was at when I calibrated, but it looks like my "ATC" doesn't work for ****.
0.0 @ 68*F (ambient temp when calibrated in winter)
-0.2 @ 78*F (ambient temp of house now in summer)
-1.3 @ 92*F (ambient temp of garage when I brewed)
Has anyone else actually checked to see if their ATC refractometer is really correcting the temp properly? An error of 1.3 Brix is pretty significant, IMO.
Anyway.... My last few batches have been coming up short on OG and I had been chalking it up to me still being on the learning curve with my new system.
However, when cleaning up after a brew session Sunday night I happened to look through the refractometer with just tap water on it and found that it was reading BELOW 0 Brix. There's no scale below zero, but I estimate that it was at about -1.3 Brix.
Thinking that my calibration was simply off, I took the thing into the house with me and started typing an email to a friend who had also used it that night to let him know that the thing was reading badly.
I looked through it again to make sure it was really off by -1.3 so I could give him a better idea about how badly it was off , but the thing was reading apprixiately -0.2... same water that I had just saw reading -1.3... All I did was carry it into the house from the garage. WTF?
So, I took it back out to the garage and sat it on the workbench for about 10 minutes and looked through it again. Back at -1.3.
Thinking back when I got it, it was winter and the house would have been at about 68*F. That was the temp it was at when I calibrated, but it looks like my "ATC" doesn't work for ****.
0.0 @ 68*F (ambient temp when calibrated in winter)
-0.2 @ 78*F (ambient temp of house now in summer)
-1.3 @ 92*F (ambient temp of garage when I brewed)
Has anyone else actually checked to see if their ATC refractometer is really correcting the temp properly? An error of 1.3 Brix is pretty significant, IMO.
The ATC must be calibrated at 68 F, then it works within a range of about 50-86 F. Now, how do I calibrate at 68 F in NC, in the summer? Voila, place the instrument in a class screw-top jar, jab a stem thermometer through the lid into the jar, place the jar in the fridge until the temp equalizes at 68 F then calibrate. Needless to say, in the summer I pull my samples and take them in the house to read. Basically you can't use them if the ambient temperatures are outside the ATC range of 53-86.
