Question/Answer
Besides seed volume variation, what would cause out of range recoveries for GGA?
There are any number of things that could cause out of range G:GA values. Dilution water quality, strength of seed, incubation temperature and probe calibration are some of the more likely causes. I would be glad to discuss some scenarios and trouble shooting with you. Email me at DavidS@envexp.com or call 1-843-576-1133 and we can go over the process.
Does the pH of the check standard solution need adjusted or just set as is? The analysts have been pH adjusting the GGA they make in house; however, I do not recall doing that in my previous position
The pH of all samples for the BOD test should fall within a value of 6.5 - 7.5. Your blanks, GGA, and seed should be analyzed as-is as the method does not call for any pH adjustment of these solutions.