I just had to calibrate some water flow meters at work and found this
useful when I did so.

One US gallon of water weighs 8.33 lbs. I wanted to calibrate the
scale, so I ran in 20 gallons of water into a container and expected
to see 166.6 lbs of water. The difference between what I measured and
what I expected was the accuracy of the scale.

If you have a resonably good bathroom scale, then put your carboy on
it, record the measure (or zero the scale...) and start filling with
water.

When the scale hits (weight of carboy) + 50 lbs, you have 6 US gallons
of water.

If you want imperial gallons, one imperial gallon of water weighs in
at 10.0 lbs.

This will all be within certain limits, of course. If your scale is
+- .01 lbs, then that translates to +- 1.28 oz (not very much).

Some will say that one gallon of water will change volume based on
tempertature (because both the liquid and glass expand and contract
based on temperature.) Personally, I have never seen much variance in
my carboys, so for this it would be best for you to measure both at a
"standard" temperature. That is, what is the temperature that you
will measure it at later? When you fill your carboy with water to
measure it, stick a thermometer in it and make sure it is close to
what you will see later before you mark your line or whatever at the 6
gallon mark. Just for grins, do this with hot water, measure, then
measure again when the water is at room temperature. Is there much of
a difference? I would be interested in doing that experiment.

I found a calculator on the internet that gives density of water at a
certain temperature. The density at 70 deg. f (21.2 C) is .998000,
the density at 50 deg F (10 C) is .999728, a difference of
approximately .002%. This temperature range will throw off your
calculation another .2 oz. Just reading the volume off of the side of
your carboy is going to be more imprecise than the variance of
figuring out what is in there based on weight and temperature.

In the end, what difference does it really make whether you have 4 or
3 bottles extra when you rack? Use it later, or just dump any extra
you have into your next batch. Mine just gets consumed or stuck on a
shelf and turned into an experiment of some kind. If you make country
wines, mix all your extras together and make tooty-fruity!

In the few batches I have made (probably 10 by now), I have noticed a
large variance in the amount of lees after primary and secondary.
Maybe this is what is throwing you off?

Having said all this, I do find it useful to have simple marks on the
sides of my buckets used for botteling and primaries to get me close.
If you have that big of a problem telling how much is in a carboy, it
will likely help but not for anything other than knowing that you can
fit this much "stuff" into this container but that same amount would
overflow this other container.

Good luck!

Alex.


(Dr. Richard E. Hawkins) wrote in message >...
> Argh. I've *got* to find a way to calibrate my carboys to figure out
> exactly where 5 & 6 gallons are (particularly 6).
>
> After 6 gallons (an all juice batch) produced a 5 gallon + 4 bottles
> last week, last night it was 5 gallons and not much more than a bottle
> (but this was a concentrate batch).
>
> I need to find a reasonable, preferably cheap, way to figure the size.
>
> I wonder if milk is an exact measure? I do get 6 gallons at once each
> week . . .
>
> hawk