I've recently struggled while trying to hit my target starting gravity and I'm betting I’m either overthinking it or going about things all wrong. First, I'm new to all grain brewing and I've only done 4 batches (all 5 gallons), so please be bear with me. Now I understand that the gravity readings during lautering vary and can dwindle down to as low as 1.010 before you should stop (in general). I also read that in order to estimate what the gravity will be after boiling based on pre-boil readings you can just take the current gravity reading multiplied by the current volume divided by the expected post-boil volume (ex. 45 * 6 gal / 5 gal = 54). To ensure decent water quality I use RO with either Accumash or a generic water treatment from my local shop. I also use a refractometer to avoid temperature implications in the readings and I’ve tested it with distilled water so I assume it’s accurate. Now, with all that setup, I’m still seeing large swings in my OG based on early readings. The gravity readings consistently seem super low right after sparging but still end up either too high or too low after cooling the boil. It’s really all over the place. 1) First, are my general rules above correct? 2) Do you have any additional guidance for how to judge your gravity during sparging/lautering based on the target OG? 3) Can you take accurate readings during the boil using a refractometer? 4) Can you boil a little longer if the gravity is slightly lower than it should be without negatively affecting the brew - I mean no more than 10/20 minutes max? 5) How much would you expect the gravity to continue to rise during cooling? 6) If the initial running's gravity appears far too low, is it beneficial to recirculate the wort back into the mash/lauter tun to further grab more sugars/dextrines/etc or is this just a waste of time? I'm probably making all this more complicated than it needs to be but I assure you, I'm still really having fun. Thanks!
I don't use a refractometer, so I can't really speak to some of the questions, but I have heard of issues with them if not used correctly. Do you happen to have a hydrometer to compare against the refractometer to see what the differences are?
Are you using brew software? Also do you correct for temperature when taking your readings? Just noticed you use a refractometer, so maybe I can't help
Good idea. I do have one but I typically only compare the refractometer to the hydrometer only when marking the final gravity since finding the FG/ABV using a refractometer involves such a complicated calculation. Next time, post boil and pre-fermentation I'll do both to see how accurate it is.
As for software, I use BeerSmith 2 and an Excel workbook with calcs based on formulas in Palmer's How to Brew to determine the mash water temps and volume. I can also use the BeerSmith app to do the temp correction for the hydrometer.
I'm not sure I totally undestand what you are doing taking so many readings, but I'll just run through my own process where applicable to your questions... Occasionally I will do a first running reading, but mostly just skip right to a pre boil reading (so all the wort is now in the kettle) - you need to be sure your first and subsquent runnings are well mixed to get an accurate reading. If you have a low gravity at this point, it's easy to adjust right in the boil with some DME. I suppose you could take multiple readings throughout (this might be you overthinking as you said), but I tend to just wait til near the end of the boil. I'm litterally just pulling a sample, putting some on a spoon, blowing on it to quickly cool, and testing it. Make sure that refractometer is calibrated. I don't often check vs. a hydrometer anymore if I hit my numbers, but I suppose if something looked odd, I would. I don't use a refractometer for FG. Yes you can boil longer. You will boil more off which will also leave you with a higher gravity. Hop utilization is your main concern when boiling longer than planned. The gravity doesn't change during cooling - I think this is just a matter of higher temps screwing up the reading. No, I would not rerun the first runnings. I would just proceed with the second running and try to correct in the kettle as mentioned above. Are you getting bad efficiency consistantly or was this a particular beer? Higher grav beers often come with lower efficiency, and it's something you can plan for and adjust your recipe.
There are a number of pieces that affect mash efficiency so its not surprising to miss your OG if you are only 4 batches in. I'm over 20 batches in and still hunting down ways to be more consistent with the mashing process. Like epk mentioned above, you can always make adustments in the boil stage if you know you were off and you really want to hit your OG. Typically that'd be adding DME if you were too low or adding water if you are too high. Usually I just let it ride unless I'm looking for a high ABV stout or a low ABV session ale.
Thanks for the feedback. I don't consistently take a ton of readings with every batch. For the various batches I've made, I've checked at various times - just trying to find the right pattern for checking going forward. I haven't run the math on my efficiency because each batch has easily made more than 5 gallons with OGs near or greater than my target OG with some tweaking to boil times to get it where I wanted it. I also haven't tried any high gravity beers yet (highest 1.063 to date). My goal is really just trying to identify the right method for checking gravity and the right methods for dealing with undershooting it.
So my takeaways: 1 - verify hydrometer vs refractometer readings (at least once to be comforatble) 2 - check gravity at pre-boil and estimate post-boil starting OG - if too low plan to boil slightly longer or add DME or just relax and enjoy whatever comes out 3 - check gravity at end of boil - if too low can boil slightly longer but be aware of hop implications I'll also start calculating my efficiency for my records.
That's the ticket. I don't use beersmith, but if it anything like any other programs, I'd think you should be able to get the numbers you are looking for without really doing any math yourself, including efficiency, pre, and post boil gravites.
One last quick question, does anyone have any idea if using a multi-step versus single step infusion generally produces more or less efficiency? So far, I've always just followed the recipe's recommendation but just wondering other's experiences.
@Gaetti, if you are interested in learning more about efficiency I would recommend that you read: http://braukaiser.com/wiki/index.ph...ity_and_efficiency_in_single_infusion_mashing Cheers!
