Gallon markings for 7 gallon plastic primary fermenter

I searched but did not find. I have one of the plastic 7 gallon primary fermenters that I suspect many people call 6.5 gallon primary fermenters (I've seen pictures of both and they look identical to me, perhaps I'm wrong). It doesn't have gallon markings on the side, and I'm wondering if anyone can tell me the measurements to add them myself. I'm looking for something like 2 gallon = 7.57 cm, 3 gallon = 15.25 cm. I made those numbers up. You may be wondering why the hell I didn't add water in gallon increments before I sanitized it, added the wort, pitched the yeast, and sealed the little bastard... well I should have. It's my first time brewing, if that's an excuse.

By the time I realized the need for it, I had to estimate by quickly measuring the diameter, and assuming straight sides to calculate the volume. I'm sure I'm off, and I just want to know by how much.

Anyway, if anyone has such markings on their bucket and feels so inclined as to measure them and post it, you'd have my immense gratitude. I feel like I might have added way too much water to the wort to get to where I thought 5 1/4 gallons might be.

Also, how bad is it to be off on the total volume before fermentation begins? Did I screw it all up? Thanks a ton! Here's a picture of the bucket for reference.

I guess it's too late, but you could just fill it with water, a gallon or half gallon or whatever increments you want, and then mark the outside with a sharpy as you go. Of course a gravity reading would pretty much tell you everything you need to know.

Edit: I guess you already thought of the water idea. Didn't see that part the first time. Still, using your hydrometer will tell you how far off you are, if at all.

BTW, welcome!

HOOTER said:

BTW, welcome!

Click to expand...

Thanks!

Ah yes, the gravity. Actually the OG was spot on, maybe like a point higher. Perhaps by some accident I managed to get it right... I boiled with 5g, then added 1g (which was all I had sitting around sanitized). I was still way shy of the 5 1/4 mark that I had calculated... but looking at the bucket I realized it's sides sloped a bit so my volume calculation is probably off a lot too.

Using a length to determine your volume is very inaccurate as no two buckets will be the same. Best bet is to fill it up 1/2 gallon at a time and mark it.

If it was an all-extract batch and your gravity was that close and it was for five gallons, then you're really close to the five gallon mark in your bucket.

Since your gravity is close, your beer will be just as close to the intended finished product. Once it's done, fill it up a half gallon at a time and mark it off for each.

Soon enough, you'll be trying to figure out plenty of other things, this is just the beginning of the obsession that is homebrewing! Enjoy the easy parts!

I used a sharpie to mark my buckets with volume measurements. This is how I know that Oxyclean will take off sharpie marks after a few washings.

Or you could use math.

I know sometimes people don't like to hear that, but you could just take a few measurements and then use a little calculus to figure out where to mark.

welcome
what about a little archimede's principle? fill a bigger container full of water, lower fermenter into container, capture all water that comes out, and measure.
I'm thinking you could use a rubbermaid container and garbage pail to capture the water.
It should be close, the thickness of the fermentor is not that much.

the other option is to relax dont worry...

good luck
capn

capn said:

the other option is to relax dont worry...

Click to expand...

This is clearly the best option. You could do the calculus and the Archimedes principle and whatever other mathematical equation you can come up with but in the end you hit your intended OG and life is good. Your not building a rocket so don't over think it. Time to sit back and let the yeasties do their magic. RDWHAHB!

Just a quick note, most markings on pails are not accurate. I've recalibrated all three of my pails, and found my "Ale Pail" one was off by almost half a gallon! It's just screenprinting... Anyway, I trust my Pyrex containers, and used them to recalibrate the pails a half gallon at a time, as suggested above. I also did this with my 40qt kettle.

IT MAY BE WRONG but I think I have read that the lowest ring from the top of the bucket often marks the size of the bucket as marketed.
Not sure it really matters since you hit your OG, just measure next time.

Not to be too geeky, but the volume of the container should be (Pi)R^2*H. I am assuming the walls of the fermenter are somewhat straight.

If you use inches for the dimension you can divide by 250 to get the number of gallons. This is an estimate.

You can also back into the heighth dimension to give you .5 gallon increments.
Height=((# of gallons)*250)/(Pi)*r^2

So a 12.5 width pot 11 inches deep is slightly more than 5 gallons.
The # of inches for 1 gallon would be (250)/(3.14*6.25^2)

Again this is an estimate but should be close.

eljefe said:

Not to be too geeky, but the volume of the container should be (Pi)R^2*H. I am assuming the walls of the fermenter are somewhat straight.

If you use inches for the dimension you can divide by 250 to get the number of gallons. This is an estimate.

You can also back into the heighth dimension to give you .5 gallon increments.
Height=((# of gallons)*250)/(Pi)*r^2

So a 12.5 width pot 11 inches deep is slightly more than 5 gallons.
The # of inches for 1 gallon would be (250)/(3.14*6.25^2)

Again this is an estimate but should be close.

Click to expand...

nice job droping the math formula bomb there. my highschool math (and for that matter chemistry and biology) teachers would be proud.

eljefe said:

Not to be too geeky, but the volume of the container should be (Pi)R^2*H. I am assuming the walls of the fermenter are somewhat straight.

If you use inches for the dimension you can divide by 250 to get the number of gallons. This is an estimate.

You can also back into the heighth dimension to give you .5 gallon increments.
Height=((# of gallons)*250)/(Pi)*r^2

So a 12.5 width pot 11 inches deep is slightly more than 5 gallons.
The # of inches for 1 gallon would be (250)/(3.14*6.25^2)

Again this is an estimate but should be close.

Click to expand...

There are 231 cubic inches per gallon................ not 250.

H.W.