Gravity/Hydrometer trouble

[Davst]

Hi we just brewed our first or second batches of beer this weekend. I've been studying up on homebrewing for the last few weeks and we felt prepared to take the plunge so to say.


Anyways, we encountered some really odd stuff. We created all our recipies in beersmith to check that they were valid and that we were on the right track.

First recipie was a Partial mash, we followed the beersmith recipie here and we were fine except that we had a bit more volume after the boil, but.. when the gravity was measured it landed at 1.030 (room temperature wort) instead of 1.042 which was where we were expecting, adding this into beersmith with the end volume game a efficiency of 5%.. ? so to save the batch i did some quick math to figure out that we'd get close to the gravity we were expecting and added some post boil extract to save it.

Even though the volume turned out to be a little larger 17.3 instead of 16 liters this should only have affected the gravity by 0.001 according to beersmith. I'm wondering where did all the extract go?


Second batch. Spooked by the abyssmal efficiency of our first batch, we were very cautious witht he second batch which was a All grain pale ale. Boil and evertything went great, we let the mash run off properly (no sparge biab) and the wort was sticky and rich indicating what should be a great wort. We took a pre boil reading cooling a sample of the wort and the gravity was at 1.026? wtf? we figured we had the same **** luck with our efficency which this time was a 39% or soemthing so we added exctract to the wort and brought it up to 1.042.

Just to be sure we did a post boil check of gravity. and got a 1.070? wtf? so we added extra water to bring it to the 1.051 we were looking for.


First obvious thing: Yeah we might have read instruments wrong.. but we checked it against a second hydrometer, we also checked for bubbles on the hydrometer.. didi the reading at the surface of the wort and I'm generally sure of that we read it right.. was concerned it was broken till we checked it against another hydrometer.

My question.. when should we check the wort for a reliable OG? and why is the OG going all over the place like this?

 

[jmprdood]

There can be problems with gravity readings on extract brews - especially if they aren't mixed very well. If you followed the recipe with correct weights and volumes, the OG should be very close.

With the BIAB, the pre-boil gravity will be less and then go up as you boil off the volume of water - did you boil off more than you had calculated? If you have a shallow, wide brew pot this can happen easily.

I'm looking at purchasing a refractometer - uses ambient light to measure SG - after using one at a buddy's house this weekend.

Cheers!

 

[BryceL]

If I'm reading this right, for your all grain batch, it sounds like your reading of 1.026 was your pre-boil gravity and you were comparing it to what the OG should have been (1.052)? The OG is the post-boil reading going into the fermenter. As you boil your gravity will increase which would have likely landed you close to your desired OG. The other thing you have to play with is the efficiency setting in beersmith which can make quite a big difference. You just need to do a few batches consistently to nail this number down.

 

[BamaRooster]

The OG should be checked after the boil, and after (if) you add any top off water. You are measuring the gravity of the wort that will be fermented. The recipe is set to a specific gravity at a specific volume. Until you reach that volume, none of your gravity measurements matter.

+1 on the mixing. If you add top off water, especially if you add extract, make sure to stir the wort well.

 

[unionrdr]

From the volumes you gave,it sounds like you didn't allow time to boil off to the proper volume. Your numbers would be better at that point.

 

[Davst]

First off, thanks for all the replies, second I'm thinking that it might not have boiled down enough either, I have a 24 Liter pot thats tall so it'll fit on a stove burner. I've normally kept a lid on or at least halfway on the pot to keep the heat in so i get a good boil.. maybe I need to do and experiment with water to see what my actual boil-off is since i suspect that it is less than in beersmiths profiles.

 

[prrriiide]

First off, thanks for all the replies, second I'm thinking that it might not have boiled down enough either, I have a 24 Liter pot thats tall so it'll fit on a stove burner. I've normally kept a lid on or at least halfway on the pot to keep the heat in so i get a good boil.. maybe I need to do and experiment with water to see what my actual boil-off is since i suspect that it is less than in beersmiths profiles.

You really don't want to boil with the lid on. I don't even cover mine partially, because it will create DMS in your final brew. You need to boil that off, and a lid will just condense it and it drops right back into the pot.

Now....to the efficiency/hydrometer issues...

If I read your posts correctly, you did remember to correct for temperature (or cool the wort) when taking your hydrometer readings. So that isn't an issue.

Have you double-checked your hydrometer in a test jar filled with 60° distilled water? Those things are mass-produced, and quality control is not always up to snuff. It is entirely possible (however unlikely) that both hydrometers are faulty. When you are getting wonky numbers, it's always (IMO) best to start troubleshooting by making sure that all of your information you are getting is correct and your measurable data is correct. Simple information like an improperly calibrated hydrometer or thermometer can really give you a headache if you start trying to figure it out from a process standpoint first.

I would also check your BeerSmith settings to make sure you don't have your efficiency constant set at something ridiculously high. Should be around 70-75%. Also, check that your batch size matches what BeerSmith has.

Something is definitely off in the calculations, though. In order to raise your OG from 1.026 to 1.042, you would have had to have added almost 2 pounds of DME. I would suggest reading this BYO article. It explains a lot of what you are dealing with in terms of calculations.

The time to get your OG is right before you pitch your yeast. However, you also want to take a pre-boil gravity. It will give you a heads up if corrections need to be made sooner rather than later. This is where a refractometer is worth it's weight in Amarillo hops.

Try plugging the phrase "predicting original gravity from pre boil gravity" into google. You'll get a lot of good information there, too.

 

[Davst]

Thanks for the tips. I will make sure to check them out. Regarding the dme. The 1 kilo added is about 2 pounds so I'd say it was correct calced.

Did a new brew this weekend which was a lot more controlled. I'm thinking bad beginner luck. Though even by following biab steps to get as much from my mash without actually doing a dunk sparge I ended up at 63% eff. Which in a way is ok but I'd like to be at at 70ish

 

[Davst]

Also. I'd love to boil without the lid. But if I do I'm stuck at a simmer. Hopefully I'll find some equipment to boil lidless