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**BrewBeemer** · 10-31-2008, 08:14 PM

Quote:

Originally Posted by Coastarine

Just for anyone working on the weight method, 5 gallons of wort going from 1.060 to 1.010 will go from a weight of 44.228 lbs down to 42.142, losing just over 2 lbs. Seem right?

water being 8.345 lb/gal

Maybe someone makes a digital bathroom scale that could give good enough accuracy.

edit: Here's a scale for weighing pets that has a 44 lb capacity and half ounce resolution for 87.90. I don't like operating that close to max capacity but just an example of something that might work.

The Weight Max scale of 35# +/- .1oz, the 50# .2 +/- plus they have many other models available for higher weights plus a tare feature. Use a higher weight scale if you have a heavy glass carboy. The scale comes with battery and a 120 volt to 9 volt cube power supply. They can be repaired here in the USA if needed.
I believe I paid $13 for the 35# on ebay under "buy now" around 5 months ago. The company had the same and different models with different days of end of sale.

**Coastarine** · 10-31-2008, 09:23 PM

Well there seem to be about a hundred of these on ebay and they're going cheap:
65 lb scale

Kaiser · 11-01-2008, 02:59 AM

Quote:

Originally Posted by Parker36

This may just be me and my background, but I have no confidence in the weight change method.

Why is that?

I might be interested in the large postal scale. This would also allow me to weigh my grain all at once w/o the limitation of 4lb at a time.

Kai

**Coastarine** · 11-01-2008, 02:38 PM

Quote:

Originally Posted by Kaiser

Why is that?

I might be interested in the large postal scale. This would also allow me to weigh my grain all at once w/o the limitation of 4lb at a time.

Kai

That's exactly what I figured, if weighing the fermenter doesn't work out I can still use it for that.

Parker36 · 11-01-2008, 03:43 PM

Quote:

Originally Posted by Coastarine

That's exactly what I figured, if weighing the fermenter doesn't work out I can still use it for that.

+1 to being able to use the scale for a more practical use post experimenting.

I guess my big problem with the whole difference in weight thing is that the change is so small (less than .1lbs) over the course of the entire fermentation process, that there is no way you can get accurate readings. I just find that there are far too many variables and that this very indirect method of measuring fermentation wouldn't stand up. Sure, you may be able to get a good idea when it is finally done, but I wouldn't use it to measure a specific gravity or anything like that.

I would equate this method to using those body fat% machines that you stand on. They work indirectly by measuring the voltage that can pass through your body since fats, carbohydrates, and proteins all have different water contents. Does it give you a rough idea of where you are at? Sure. Would one ever be used in any kind of clinical study where the numbers really matter? Probably not.

I'm not trying to trample on the whole weight idea, maybe we are just looking for two different things.

Parker36 · 11-01-2008, 04:49 PM

I was thinking about what The Kaiser said earlier about CO2 in the liquid screwing with the buoyancy of a submerged hydrometer type thing and was wondering how this dissolved CO2 affects a standard hydrometer reading and how large the affect is.

**BrewBeemer** · 11-01-2008, 07:47 PM

Quote:

Originally Posted by Kaiser

Why is that?

I might be interested in the large postal scale. This would also allow me to weigh my grain all at once w/o the limitation of 4lb at a time.

Kai

Coastarine; this might be of some intrest to you;

Besides the scale I posted above, have and enjoy is if you go to http://www. Amazon.com: Online Shopping for Electronics, Apparel, Computers, Books, DVDs & more, you'll have to ding around with the search section type in digital scales, yes a PITA. Check out the Maxweight 75 lb Digital Postal Scale they have a 75# for your grain weighing plus it's "Readability" is .2 oz / 5g. Price $28.99. This is before shipping and like the 35# Maxweight I posted above it comes with a 9 volt battery and a cube 120 volt power supply. This 75 pounder would handle those glass carbo tare weight plus contents that was mentioned before. Weightmax even have repair facilities here in the states not shipped out of country. Like everything else it's made in China that's what's on the box of my Maxweight 35#, +/- .1 oz accuracy scale.
In the future the US of A may become the US of C? Just a thought after walking thru Walgreens reading lables on everything waiting for a prescription order. Home Depot's Irwin (a US manufacture) the magnetic tip extensions are made in China. Not a rant here just what I have seen now back to the scales.

**Coastarine** · 11-01-2008, 08:45 PM

I got one of the 76lb .2oz resolution ebay scales. Some of them are free shipping and the bidding usually ends at 25. The one I got was 14.95 shipping and I got it for 9.95 making my total 24.90. If it isn't a piece of crap then that's a good deal to me.

Kaiser · 11-01-2008, 10:21 PM

Quote:

Originally Posted by Coastarine

I got one of the 76lb .2oz resolution ebay scales. Some of them are free shipping and the bidding usually ends at 25. The one I got was 14.95 shipping and I got it for 9.95 making my total 24.90. If it isn't a piece of crap then that's a good deal to me.

You'll need to run some experiments for us once you have it. Like put a full carboy and a cup of water on and see how accurate the weight changes as you remove tsps (5 g each) of water.

I ran the concept through a spreadsheet last night and found that every 10g loss equates to rougly a 0.1 Plato (~ 0.4 gravity points) drop in a 5 gal batch. This is better than my standard hydrometer. Apparently there are cheap enough scales that can do that.

But if the Scale doesn't stay on all the time you'll need to lift the carboy/bucket and tarre the scale. That might be annoying. If it was to stay on we have to worry if it would drift out of calibration.

Ideally I'd like to use a cheap scale (or the force plate that was listed although it is rather , hook into the logic to get the sensor reading and connect this to a small computer with display. Not sure how much these computers would cost. Then write a program that allows you to record the weight, enter the OG and allow for sampling or Kraeusen skimming which removed mass that doesn't correspond to a SG change. if the overflow bottle/bucket for blow-offs are on the same scale, that system would also work if a blow-off tube has been rigged.

One caveat I know of is that this measurement is indirect by measuring the amount (i.e. weight) of CO2 that escaped from the fermentation. I would have to find out through experiments if the slight supersaturation (more CO2 in solution than there should be at equilibrium) makes a big enough difference that it matters.

If it could be build for less than $150 I'd be up for it. Most of the parts would be reusable for other tasks anyway.

Kai

**Coastarine** · 11-01-2008, 10:49 PM

I also thought about leaving the carboy on the scale and even if it was turned off I think the constant strain could be bad for it, so here's the plan:

I'm going to just have a simple excel spreadsheet. I'll weigh the better bottle and any blowoff rig, enter that into the spreadsheet. I'll use my hydrometer (or refractometer if I have one by then) to take an OG. This will give me a weight like I was talking about earlier. I'll weigh it periodically, and when fermentation is well over I'll take another gravity with the hydrometer, and we'll see how accurate this is.

As far as the dissolved CO2, I think it will be very consistent and easy to compensate for. Naturally the volume and temp of the beer decides how much CO2 stays, and that should be almost exactly the same from batch to batch, or easy calculated.