I'm not getting good results with vaporized oxalic acid and would like your thoughts. I've done 4 OAV treatments and my way too high (20 to 24 per 300 bees) mite number aren't really coming down (I'm only counting one hive but I am treating all six). All hives have screened bottom boards (well sealed during the treatment), slatted racks, and two deeps, except one that only has one deep (not the one being counted). Two overwintered and four were splits from those two this spring/summer.
I have a standard cheap 12V vaporizer and 98.5% oxalic acid from Amazon. For the first three treatments I was using a lawn tractor battery and it was too weak for my six hives. It took 4 to 5 minutes to vaporize in a test burn and after the first hive or two would leave a brown/black residue. There would be some dead mites on the screened bottom board covers, after 24 hours, but not hundreds. However, after 3 treatments over two weeks, the mite count hadn't changed (see below for details).
I figured that the battery was the problem so got a 300W 12V plug in power supply. Test burns looked much better, 3 to 4 minutes, and no residue was seen after either test burns or actual hive treatments. I was therefore very disappointed that 3 days after my first treatment using the power supply the mite count still hadn't dropped appreciably.
Details are below:
7/27: Mite counts 24/300 (first time I counted this summer; the summer got away from me a bit)
7/28: First OAV (battery)
8/3: Second OAV (battery)
8/8: Third OAV (battery)
8/10: Mite counts 24/300
8/16: First OAV with power supply
8/19: Mite counts 20/300
I've ordered Formic Pro and will put that on as soon as it arrives and will stop the OAV treatments for now, but I would still like to understand what is going on with my OAV failures.
1) The oxalic acid I have turns brownish/dark in my test burns, which is different from what I have seen in online videos.
2) The oxalic acid I have is flakier/stickier than the powder I see in online videos.
3) I seal up the hives pretty well, but am able to see small wisps coming out of various places on the hives, so it seems that the vapor is moving about.
4) Now that I am using the power supply, the chamber is empty when done, although the chamber is now darkened to a sort of chocolate milk color.
Any thoughts? Is my oxalic acid bad? Am I incorrect in thinking that the counts should have dropped substantially 3 days after what seemed like a quality treatment with a good power supply?
Thanks for any suggestions you might have.