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-   -   Mash PH and Original Gravity (http://www.homebrewtalk.com/f36/mash-ph-original-gravity-305983/)

clcondawg 02-20-2012 03:28 AM

Mash PH and Original Gravity
I've made 4 all grain batches and every time I've had to add sugar during the boil because my gravity has been way low. I just recently made an IPA with an estimated OG of 1.075 and it came out at 1.050. Really dissapointing. So I started thinking about all the things I could be doing wrong. I realized I have never adjusted my mash pH. I use the really cheap pH test strips and it always seems to read about 6 - 7, but I don't know how to fix it so I just keep going. Could a high mash pH have that much of an effect on my OG, or should I continue to search my brain for previous brewing errors?

Revelator 02-20-2012 04:05 AM

From the sounds of it, your low OG is probably not entirely caused by your pH levels although if it is truly at 6-7 after mashing you are going to have issues with conversion, and ultimately the amount of fermentable sugars available in the wort - From what I understand the starches would still affect your gravity readings, which still makes me think that there may be other forces at play...Your low sugar extraction could be one of many things...How do you rinse your grain? What temperatures do you use?

As a quick and easy way of getting the desired pH level (optimally 5.2), you can adjust with food grade phosphoric acid...others might recommend a product called 5.2 stabilizer, but I havent had much luck with it - I typically use RO water with the addition of about 1 tsp of calcium chloride and always hit the proper pH without adjustment

If you want to see if you are actually achieving a good conversion after mashing...try an iodine test - Just remove a small sample and place a couple drops in the wort...If it turns black/purple it means that you still have starches present, and would most likely need to look into adjusting the pH...otherwise the iodine will just dilute

Hopefully this is helpful...otherwise I apologize for the rant

mabrungard 02-20-2012 01:30 PM

If the mash pH is really that high, there may be some issues with conversion. But I'd be expecting that there would also be taste issues too, such as coarseness, harshness, or astringency.

You should try and find out about your water so that you can make a better assessment of what you should be doing to your water for brewing.

RM-MN 02-20-2012 01:41 PM

Your pH readings may be due more to the pH strips than the actual pH of the wort. Some people have reported that the pH strips reading is way off. I'd question the quality of your crush on the grain before I'd think you pH was the problem. You could get a digital pH meter for not a huge sum and try that in your mash. My blond ale showed a mash pH of 5.6 and it converted just fine.

dezman 02-20-2012 01:51 PM

Are you measuring OG before your boil. Before the boil the gravity reading will be lower because you should end up with more volume then 5 gallons before the boil. The OG should be measured post boil were your volume should be close to 5 gal. This might be part of your problem. Also remember to correct for temperature, hydrometers are calibrated at a certain temp and any deviation from that temp needs to be corrected by using the conversion chart (you can search for this chart).

My guess is if you do both of the above you should be quite a bit closer to you target gravity. If not I would then look into other thigs such as crush, PH, mash times/temps, ect.

clcondawg 02-20-2012 04:43 PM

Thanks for all your replies. My temperatures have been good. 153 +/- a few. As far as rinsing, I did BIAB for the first 2 and then the second two rinses have been kinda wierd. The third batch I did an infusion mash in my brewpot but then for the sparge, put the grains back in the bag and let the bag sit in 168 degree water for fifteen minutes. For my last batch, I built a cooler mash tun. But for the sparge, we drained the wort completely and then maintained the drain valve open while sprinkling hot water over the grains.
There hasn't been anything wrong with the taste of the beer.
I have suspected the pH strips. What is a good pH meter to use that isn't extremely expensive?
A couple of you guys mentioned the crush too. Are you referring to when they mill the grains at the supply store? I have wondered if having the grains crushed 2 or 3 days before I actually steep them was an issue. Would that be, or are you talking about the quality of the crush?
Thanks again.

RM-MN 02-20-2012 05:05 PM


Originally Posted by clcondawg (Post 3808004)
A couple of you guys mentioned the crush too. Are you referring to when they mill the grains at the supply store? I have wondered if having the grains crushed 2 or 3 days before I actually steep them was an issue. Would that be, or are you talking about the quality of the crush?
Thanks again.

If you had your grains crushed a year or two early I would worry but a day or 3 won't hurt a bit. When I bought grains at Midwest they suggested it would be best if I used the crushed grain within the month.

The quality of the crush is what I would worry about. When you mash you can only extract the sugars that have beer converted by the enzymes and for the enzymes to work the grain has to be wet. If your crush is too coarse the water takes a long time to get to the center of the particles and it takes more time yet to get the sugar out. The LHBS gas a quandry. If they don't crush fine enough then efficiency suffers and more grain is needed for a recipe (but they sell grains) while if the crush is too fine you will end up with a stuck sparge (in a conventional mash tun). Stuck sparges make people unhappy and if it happens too much the people will find a different LHBS and once lost the original LHBS won't get them back. That is why a bunch of brewers have their own crushers, they can get the crush that is best for their system.

Homercidal 02-20-2012 05:19 PM

I think the majority of efficiency is in the crush. Many people get subpar efficiency due to a very poor crush at the LHBS. It's possible they have a valid reason for this besides wanting you to buy more grain to make up the gravity.

At any rate, you may want to invest in a $80 pH meter if it really bugs you. I don't think it will affect the efficiency as much as a proper crush, but if it's off by as much as you say, it might help the flavor and the efficiency to get it where it should be.

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