Questions about OAV procedure
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  1. #1
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    Default Questions about OAV procedure

    After having done two disappointing rounds of MAQS since August (no apparent damage to queens or brood, fortunately, but modest and only short-lived results on the mites), I decided to try a series of OAV.

    I have the Varroacleaner. Bought a new battery, and gas mask for the occasion. Test-fired it and started in this morning.

    On the first two hives (one with 3/4 tsp OA and one with only 1/4 tsp, due to size of colony differences) things went as I expected.

    The third and fourth did not. The third one had a full teaspoon of OA. When I withdrew the wand, it and the cookie sheet it was sitting on, were covered with kind of white fluffy "snow", as if the OA had not sublimated fully. There is additional visible fluff at the far end of the floor.

    I checked the battery strength thinking that perhaps it wasn't giving enough juice. It was good. Actually I didn't do the checking, my dear husband, the electrician, did; I have no idea how to use a multimeter. I also thought perhaps a whole teaspoon was too much.

    Fourth hive required only a half teaspoon. The same thing happened, though less so, and with more flat flakes of OA scattered around on the cookie sheet. In this case I went to particular care to make sure the wand and cup were perfectly flat, centered, etc., so I can rule out displacement, or tipped reservoir.

    Can I conclude that in the last two stacks, the full dose wasn't dispensed? I did notice that for these two, in contrast to the other two, there was only minimal "buzz-roar" during application.

    On the good side, none of the colonies seemed madly unhappy during and after the treatment. It was quite cool (@ 50F) so they weren't eager to rush out afterwards. I have fresh stickies in so we'll see what drop I get.

    Just would like to know if the "snow" is a problem, or simply normal ops. If it was a deficient application I can just add another one on to the end of the series for those two stacks, I guess.

    The process seemed quite fiddly and time consuming, but I can see that was mostly my own unfamiliarity with the technique. I think that I will fabricate some sort of wide, flat, sheet metal base with some clips or stops to hold the reservoir in perfect position during treatment. That will save more than half the time and effort at insertion. Then one could insert, plug the entrance, light up the wand, and start the timer. And then for a minute or so, you could be preparing or ventilating another hive.

    Thanks for any advice about the OA "snow" you can offer.

    Enj.

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  3. #2
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    Default Re: Questions about OAV procedure

    Your pan may be a bit small for that large a dose and it is overflowing during boil off. That was a problem with one of the first ones I made. Current one is larger. Did DH do a check of battery under load? If for some reason current is reduced the acid will possibly bubble up, crust over and freeze. I found I could just sprinkle some water in the cup, not completely cooling it, dump in the next charge and the wait time would be nearly zero before it started to gas off. Speeds things up a bit but dont tell anyone I advised that!
    Frank

  4. #3
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    Default Re: Questions about OAV procedure

    Frank,

    Thanks for quick the reply!

    I wondered about the pan size on the full teaspoon dose, but then I also had the problem with a half-tsp, but not with the earlier, three-quarter teaspoon dose.

    Yes, my husband did test the battery under load, both before and afterwards, and it seemed fine. The pan seemed a bit loose so he wondered if there was only a single ground wire that was not in perfect contact...... It's on his list for taking apart this evening. In some ways, now, I wish I had sprung for the Varrox model, not the somewhat less expensive Varroacleaner.

    I did clean (in water) and then fully dry off the pan between applications; I can try it your way and see what happens.

    Of course, the "snow" had to appear on the two hives in which I have the most concern about mites, not on the two I was just treating under the principle of "treat the whole apiary, not just some of them". It's always something! Perhaps it did do some good, anyway, so the five-day wait for the next treatment won't be too harmful.

    Enj.

  5. #4
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    Default Re: Questions about OAV procedure

    This is my first year and I have successfully treated 3 hives with one complete round of OAV, 3 treatments 5 days apart, so I'm not a seasoned expert but have done it. My comments would be that your observation isn't 'normal'. I would suggest as did Crofter that you perhaps overloaded the pan and the OA could not sublimate properly. A full teaspoon sounds like a lot to me. It could be that with a large amount of OA some OA gets spat out of the pan during the sublimation. As you note, things went well with a smaller amount of OA. You could test that by loading the vaporizer with the amount you used and test-firing it again outside the hive to see what happens. I'm also not sure that it is a good thing to lay the vaporizer on a cookie sheet since the cookie sheet will bleed off some heat from the vaporizer and perhaps cause the vaporization to be less brisk and take longer. Perhaps place the vaporizer on a small tile on the sheet to insulate it from the sheet. But again, you can test that outside the hive.

    edit - I type slow, just saw your second post.

  6. #5
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    Default Re: Questions about OAV procedure

    I havent had my hands on that model. The one from Heilyser has a thermal gap between the pan and the gard or stabilizer underneath. I made a similar unit and stuffed the gap with fiberglass cloth. I guess I melted down some ladder comb and it soaked the fiberglass and became a heat transfer instead. I pulled out at the prescribed time and found some of the charge still in the pan. Pulled out the wax soaked fiberglass and things returned to normal. On the Heilyser model the pan is held tight to the glow plug tip by a set screw. That needs to be checked for tight. The connections to the leads need checking too but your electrician should be on top of that. I am not sure if much of this applies to your model or not. Other than that, do some practice runs out of the hive and observe what is happening.
    Frank

  7. #6
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    Default Re: Questions about OAV procedure

    I have the varrox vaporizer and noticed that it was taking longer last week when I treated 10 hives, so I put a volt meter on the battery as the vaporizor was hooked up (under load) and the voltage dropped just under 12volts and still had plenty of power, I think the longer treatment time was due to the lower ambient temp,,it was 50 deg compared to 75 deg that I had during the last treatment...
    The snow you spoke of I think is normal, as the vapor condenses on the coolest thing which happened to be the cookie sheet, I've heard that is does the same thing to the frames, although I've never inspected right after a treatment, I have noticed the bees coming out of the hive during the treatment and were covered with the "snow"
    Once while not using a timer and just waiting till the smoke slowed down ,I pull out the vaporizer too soon and saw the boiling liquid in the cup to which I reincerted the unit and waited a few more minutes.....Just my own observations...

    ==McBee7==

  8. #7
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    Default Re: Questions about OAV procedure

    The cookie sheet will dissipate the heat. Perhaps use a piece of flashing or very heavy duty aluminum foil if you are covering screened bottom boards. Also, spread the OA evenly out on the pan, don't lump it. A teaspoonful is too much. One half of a teaspoonful is almost exactly a gram.
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  9. #8
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    Default Re: Questions about OAV procedure

    OK, if a teaspoon is too much, but then why did three-quarters of a teaspoon work OK, while the half teaspoon treatment produce "snow"? That doesn't make sense to me.

    And I have to use at least a full teaspoon on two of my hives which are four deeps (or even larger). For this initial round I actually used a reduced (proportional) dose for the two largest that was about one box less than what they actually need based on their sizes. (I.e., the four deep got a three by 1/4 tsp dose; the two deep plus five medium stack - which by my count is the equivalent of 4 2/3 deeps - is the one that got the full teaspoon.) On that last colony I did move the current brood area boxes down from the top towards the bottom last week to put them closer to the vaporizer. I know OAV doesn't penetrate the cappings, but I fgured that the bees would be clustered around the brood, so I'd get better coverage where it's needed the most.

    I carefully spread the stuff out (without packing it down). I can use a something beside the cookie sheet, though it worked very well. I've got designs in my head for a kind of rigid platform to hold the cup in perfect position, without all the fidgety adjustments to place it and keep it from tipping upwards (weight of the handle overbalances it, unfortunately). I will think how to do that without using up any of the heat in the pan.

    I did do a test burn with a whole teaspoon, before I started. It burned just fine and turned into white smoke, as I expected.

    One thing someone mentioned above, about waiting for the smoke to die down. I saw no smoke escaping from the hives. I had covered (with plastic plugs) the two upper vents; closed the front entrance with the wooden entrance reducer wrapped in paper towels and carefully closed up the back entrance around the wand, so no smoke would be in my face during operation. Did I mess something up - all of the visible vapors remained in the hive. I thought that was the point. My girls are champion propolizers and at this time of year I am not scraping the stuff off at the box joints, either.

    Glad to hear the "snow" is not grossly abnormal, but perhaps just a slight undercooking. It was the reverse possibility that had me worried.

    Can't wait to take a peek at my boards tomorrow in the a.m. - Might even sneak out with a torch tonight!

    Enj.

  10. #9
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    Default Re: Questions about OAV procedure

    Getting into total speculation now. As McBee7 stated the OA is supposed to sublimate and then condense within the hive as very fine crystals of OA. If what you are seeing as snow is condensed OA then maybe the vapor did not distribute well within the hives where you found snow on your cookie sheet. The vapor should spread throughout the hives by convective air currents in the hive. Maybe the air currents, set up by the vaporizer, the bees, and general ventilation were insufficient to distribute the vapor. Try not plugging the upper ventilation openings and see if any OA vapor appears. If it does, you know you got vapor up there and you should be good to go. If it doesn't, at least it might increase circulation some and decrease the snow at the bottom. Also, if the snow is a very small fraction of the original OA then I wouldn't much worry about it.

  11. #10
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    Default Re: Questions about OAV procedure

    When the temps are low, the fumes won't flow as when the temps are higher....... but they do flow inside the hive. I've also noticed that when using my or my competitor's (yes, I have purchased one of my competitor's for comparison purposes).......Also, the OA in these vaporizers is meant only for (at most) 2 grams (1/2 teaspoonful) at a time, so if you need 4 grams (for 4 brood chambers), vaporize twice.... 2 grams each time. I have also noticed that with successive treatments the battery does not vaporize as well as the first several. When I have the vaporizers hooked to my truck battery (with the engine running) they vaporize just fine.......

    If I were doing a stack of 4 (9 or 10 frame) brood boxes, I'd vaporize 2 grams then do the next 2 grams right afterwards...
    Last edited by snl; 10-20-2014 at 10:31 AM. Reason: Don't ever, ever drink bloody Mary's before answering a BS Question
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  12. #11
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    Default Re: Questions about OAV procedure

    Well, OK, so if the vaporizers are (quote) "meant only for (at most) a gram at a time", which is the dose for only (at most) two brood (or other boxes), that would imply that the OAV is optimally used on hives with only a single brood box, but could be stretched (at most) to incude a double brood chamber.

    That certainly doesn't seem at all consistent with many comments here about the actual OAV usuage, unless people are not using a half-gram OA per box as the basis for treatment dosage.

    This confuses me, because of earlier answers (here on BS) to my questions about dosing.

    But if my hives are bigger, and they are, then how should I apply the additional amount of OA if, in fact, it's needed? Serial burns (preferred interval between them - minutes? hours? days?) Or simultaneous burns -but could that result in harmful, too-great a concentration of OA vapors?

    It's a very useful tip to leave the upper entrances a bit open to set up a stack effect to help draw the vapor upwards. I can easily do that.

    So, when I was doing my before-bed rounds on the farm I went down to the hives to pull the stickies for a quick check, and ................

    Well, I'm here to tell you that OAV obviously cured any mite problem I had. It must have literally vaporized every last one of them in my huge hives, because there was NOT A SINGLE MITE, (dead or alive) on any of the stickie boards. Which is weird, because they normally drop a few every day - and the big hives, being ginourmous, drop more than few even when their roll numbers are tiny, just because there are so many tens of thousands of bees in those boxes.

    I will check again this afternoon, after a 24-hour period has elapsed. But it was nice, if somewhat puzzling, to see no mites on my stickies, for a change.

    (Don't worry, I know the OAV treatment doesn't literally vaporize the mites ... I was just bemused to see none, when I was expecting lots of dead ones.)

    Enj.

  13. #12
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    Default Re: Questions about OAV procedure

    Late afternoon check yesterday (24 hrs + from OAV treatment) of my stickies showed dozens (but not a hundred) of dead mites on three out of four.

    The fourth one is the biggest one with the most amount of "snow" and, of course, the one with the biggest mite problem (by sugar roll). Phooey! I am going to just count it as a "fail" and adjust my technique and start its treatment again, adding a fourth one on at the end to account for this initial mis-fire.

    Still not sure how to accomplish getting the correct proportional dose in a large, multi-box hive if the pan will only burn enough OA for "at most" two boxes. Any further suggestions?

    Very satisfying to see all those dead mites on my stickies. Especially since each of those hives was "officially" well below any treatment threshold due to earlier treatments. Those dead mites are bonus-points, I think.

    Enj.

  14. #13
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    Default Re: Questions about OAV procedure

    FWIW, I find my mite counts/24 hours increase over several days after using OAV. If you like what you found after 24 hours, just wait! I, too, have only tried it this year and can only reference my personal experience. I also keep my vaporizer connected for 3 minutes vs 2.5 to assure complete sublimation. I have not looked at your brand of vaporizer but with the Varrox, I do not use a cookie sheet.

    Cheers,

    John
    11 yrs, TF 6 yrs, moved to OAV in 2014, MAQS 2016. 6 hives and 5 nucs Zone 4B
    www.nhbees.wordpress.com

  15. #14
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    Default Re: Questions about OAV procedure

    I agree with John, my largest drop count is the next day, but it continues for 3 days. As far as HUGE hives.... I don't have any that have brood chambers larger than double deeps. Even if you stack a bunch of honey supers on, mine are still just double deep brood chambers. I don't treat with OAV when the supers are on. I treat in the spring as the build up starts, and I treat in the dearth and again in late fall, all after I've removed the supers.
    Robbin NW Florida(8A) / 14 hives / 5 Nucs / 6th Year / T {OAV & MMK}

  16. #15
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    Default Re: Questions about OAV procedure

    Quote Originally Posted by enjambres View Post
    Still not sure how to accomplish getting the correct proportional dose in a large, multi-box hive if the pan will only burn enough OA for "at most" two boxes. Any further suggestions?
    On your 4 brood box hives (still trying to find out why you have 4 brood boxes ) but anyways, I'd do two, 2 gram treatments, one right after the other. The "snow" I believe you saw on the cookie sheet, were the reformed crystals from the OAV. They would be very obvious on a cookie sheet (not so much so in the rest of the hive)..........
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  17. #16
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    Default Re: Questions about OAV procedure

    Thank you, Robbin, for your comment about the 3-day accumulation of dead mites. I look forward to pulling the boards in another day or so.

    The thing is that I don't have "honey supers" in the conventional sense of whole boxes that are exclusively for honey that can be removed by a beekeeper, so I have nothing I can take off. My hives consist of various boxes where they live and brood and store stuff, pretty much where ever they please. And there is no area of the hive that is not packed to the gills with bees at the moment. If I took any of the boxes off and removed the bees from those frames, I'm not sure where the bees would go and in my area they would not survive a night in the open at this time of year. The population will get smaller and more densely focused over the winter, but not now at the end of a bountiful nectar-collecting year.

    And OAV only affects the phoretic mites so having a large number of bees out of the box during treatment would seem to defeat the purpose, reducing the overall effectiveness.

    To compound the problems, this particular hive is also a top-entrance only hive so conventional bee escapes won't work to concentrate the bees downward and permit a (temporary) reduction in the number of boxes.

    I've considered temporarily dividing the stack into two parts before every treatment and then treating each part separately before re-combining again, immediately afterward. The logistics of that seem daunting and I think it would result in a lot of flyers not being exposed during treatment. I suppose if I did this during relatively cool weather (< 50F) it would reduce the out-of-box bees, but at the same time that would then expose the whole hive to the substantial risks of chilling, particularly for any bee that did fly out during the division manouever.

    Later today, if it stops raining, I will do some calibrated tests to see what the maximum sublimation capacity of the pan actually is, at least in the open air.

    If my electrician husband confirms that the power source is more than adequate under load, that the device's wiring is intact and perfectly functional, and if I re-confirm that the pan can handle at least a full one-teaspoon charge of OA, then it will come down to figuring out a way to satisfactorily expose the full stack to the vapors. Just trying to break down the factors to make sure I identify what needs to change in order to treat my Big Girls.

    Enj.

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