So I took a chance on the HI99104 meter, hoping I could get something workable for less than a hundred bucks. I've used it for about 6 brews now, and after learning how to use it consistently decided to run a stability check. Having sat in storage for the last week it was reading 4.10 and 7.07, so I calibrated to 4.01 and 7.01 at 20C. I did take temperature readings during the tests, but due to the entire spread being 20.0 and 20.6 I am not going to add those to the data table. Please note that the first 20 minutes of readings were done with the probe left in the 7 buffer, and all subsequent readings where done after the probe was rinsed in DI water, placed in the storage cap and rerinsed before being placed in the buffer 5 minutes before the reading was noted. This is because this meter is pretty slow, it consistently takes that long to stabilise at a value. Some of the readings with a 30 minute difference were given 10 minutes to stabilise, just to see if there was a difference between 5 and 10 minutes to read. There was not. On to the data.
pH. Time(minutes from calibration)
0. 7.01
2. 7.01
5. 7.01
7. 7.01
10. 7.01
15. 7.01
20. 7.01
Beginning of 5 minute readings
30. 7.01
40. 7.01-7.02 pulse (would not settle on one or the other,2-5min)
50. 7.01-7.02 pulse
60. 7.01-7.02 pulse
90. 7.01
120. 7.02
150. 7.01-7.02 pulse
180. 7.02
210. 7.02
240. 7.02
270. 7.02-7.03 pulse
300 didn't get measured as I was busy setting up my brew day
330. 7.02
I stopped testing at this point because i was getting busy.
Overall I feel pretty comfortable using this meter for brewing, especially considering I got it for $40 shipped. Even between samples being tested today I have not seen any buffer reading more than .01 off of initial calibration.
pH. Time(minutes from calibration)
0. 7.01
2. 7.01
5. 7.01
7. 7.01
10. 7.01
15. 7.01
20. 7.01
Beginning of 5 minute readings
30. 7.01
40. 7.01-7.02 pulse (would not settle on one or the other,2-5min)
50. 7.01-7.02 pulse
60. 7.01-7.02 pulse
90. 7.01
120. 7.02
150. 7.01-7.02 pulse
180. 7.02
210. 7.02
240. 7.02
270. 7.02-7.03 pulse
300 didn't get measured as I was busy setting up my brew day
330. 7.02
I stopped testing at this point because i was getting busy.
Overall I feel pretty comfortable using this meter for brewing, especially considering I got it for $40 shipped. Even between samples being tested today I have not seen any buffer reading more than .01 off of initial calibration.