I just ran into this problem myself. I have been noticing the green snot in the bottles and noticed some inconsistencies in my tests so I started just using sera drops for alk and everythings been great. Decided to try the hanna kit again and I noticed the green snot in the bottle and my test came out a lot lower than expected. So swapped to a new bottle of reagent and my dkh read 1 point higher. Pretty disappointing so I will stick with the one bottle sera kit which is much more reliable.