There are differences between your method and Allan's write up on Beesource.
His number is 8 liters for 250 of the DL-50s which amounts to about 30ml
per pad and releases the formic at about 7ml per day for 4 days.

Your amount is 40ml per pad so it might release a bit more (unlikely
because the holes limit the release) but would last a couple of days longer.

What is interesting about your experience is that you also use Apivar but
when you did not and only used the Formic you still have very good results,
which couples with Allan's experience but his requires 4-5 treatments to
cover the brood cycle.

My guess is you leave the strips on between treatments (removing the old
one and replacing it with a new one) and remove them all or let the bees do
so five days or more after the last treatment.

I had excellent results using Alan's directions but it did require 5
visits  and I looked for something that required fewer visits. Apiguard (
Thymol) worked but everything picked up the smell. The fume board treatment
with 100 ml of about 45% formic worked but not this past year plus it is
hard on the bees since it is an all at once at high concentration of fumes
treatment while the dryloc pads are over an extended period.

So I am going back to the pads and try Dave's method on one hive and Alan's
on the other.

I think the key to Dave's method is that he treats more than once, so he
gets a good knock-down in the early season so a later treatment has fewer
mites to worry about, while the longer duration but only one time per
season treatment does a better job but may be too late in our current world
of viruses.

BTW, if you do have 85% formic the easiest thing to remember on how to
dilute it is - to get 100ml. it is 75ml (3/4) and add 25ml water so 3/4 is
acid and 1/4 water. Allen's ratio is based on 8L so his is 6L 85% and add 2
more liters for 8L to treat 250 Dry-loc pads.

For those who like computing, an easy way to remember what to do is that
each pad is about 30ml (Allan's is actually 32) so multiply 30 by the
number of pads, say 100 which =3000 ml (3 L) of solution. Multiply that by
3/4 or .75 which gets you 2250ml. So take 2250ml of 85% acid, add water to
get to 3000ml and all done.To use Dave's method just change the 30 to 40.

Bill Truesdell
Bath, Maine

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