Another low sg question (sorry)

[howard86]

Hi all,

I've been looking through the forum at people asking about getting low sg from all grain brewing and I'm not entirely sure what my problem is.

I've done a few all grain batches but they always come up significantly lower in the sg than the recipe suggests. I've been adding dme but need to figure out what i'm doing wrong.

My last brew was for 2.5 gallons:

5lb Pale malt
5.6oz crystal
.50oz Nugget @60mins
.25oz Chinook @15mins
.25oz Cascade @15mins
.25oz Amarillo @15mins
.25oz Chinook @0mins
.25oz Cascade @0mins
.25oz Amarillo @0mins
Wyeast American Ale starter (seems a bit pointless now ahaha!)

I mashed 6.66l at 66oC for 1hr, then fly sparged with 12.87l at 80oC. I used a calculator as I'm not clued up on amounts of water needed still.

I got about the amount I'd planned for. Did a gravity reading and it showed something around 1.020. Boiled and it had gone to 1.038.

The recipe when put in on beersmith said 1.055 so mine was colossally off as usual. I had forgotten to get any dme so only had enough to bump it up to 1.042.

As far as I can tell the grains are crushed fine, I sparged slowly (doesn't seem to make a difference if I batch sparge or sly, it's always mega low).

I've seen and had people comment on a post in the past here about the water. Its hard water here but I don't know mineral readings or such. Is this likely to be what is making the suger extraction so low?

If there's any more information I've missed please let me know too,

Many thanks
Howard

 

[JimRausch]

I'm guessing at the %, but I want to say that 65% of lower than expected gravity problems are due to poor crush. And the other 32% is incorrect volume additions. Maybe 2% incorrect mash temps, and 1% incorrect mashtimes. There's just not other things that can give you major changes.

 

[howard86]

Thanks for the reply, if there is an issue with the malt, I guess it'll be the maris otter. I've been using a big bag of it which is about 45kg's worth. Whereas previously I'd just been getting 3kg bags. I could pick up some of the smaller ones and do an experiment at the weekend and see if it makes a difference or not.

 

[rburrelli]

On the malt.... I recently heard that if you are using malt that is already crushed from a sack, there could be a lack of efficiency caused by settling of the milled grain to the bottom of the sack meaning more husk material in the top of the bag.

 

[dmtaylor]

5.35 lb malt is kind of a small amount for a 1.055 recipe for 2.5 gallons. Try closer to 6-6.5 lb and you should achieve a better result.

 

[9Kegs]

I ran your recipe on Brewers Friend and at 70% efficiency it came up with a 1.055 OG. I was guessing on the crystal malt ( I used crystal 10) because you did not say which crystal ( there is quite a few). My thoughts are with using lighter malts and not doing some type of acid addition your PH is going to be way too high for good conversion. As previously mentioned mash temps, water volumes, and CRUSH are key.

 

[howard86]

Thanks for the replies again. There is a chance the husks are higher up. There is a lot of finer powdery bits too whenever I scoop out grains to use, but I'm relatively new to this so not sure if that's usual or not.
@dmtaylor - I just halved a recipe that I had found for a basic 5 gallon batch, and changed some of the hops. I lowered the grain amount slightly as I didn't want it at 6% (it was meant to be for the upcoming tennis club christmas do so didn't want everyone only going with one or two ) What's the best way of going about a half batch from a 5 gallon one please?

 

[howard86]

@9Kegs - I don't remember the crystal malt type..the homebrew place I get it from doesn't do the whole 10l, 20l thing, it's mostly crystal, dark crystal or extra dark crystal in it's terminology. This was just the standard crystal so I guess it's around 20-30l maybe.
I could get some kind of water test to see what the pd is, I guess it's pretty alkaline with all the lime in it round here though

 

[TurnipGreen]

What sort of mash and lauter are you doing? Are you sparging or rinsing the grains after the mash?

Describe your process a bit.

 

[grampamark]

Your strike and sparge volumes totaled 5 gal for a 2.5 gal batch. Unless you boiled off a lot I think the water volume may be your problem.

 

[bracconiere]

My thoughts are with using lighter malts and not doing some type of acid addition your PH is going to be way too high for good conversion.

with my hard water i usually have to add bicarbonate to get get the pH up.....

to the OP how do you sparge, or in what?

Your strike and sparge volumes totaled 5 gal for a 2.5 gal batch. Unless you boiled off a lot I think the water volume may be your problem.

now that he mentioned it....+1

 

[dmtaylor]

@dmtaylor - I just halved a recipe that I had found for a basic 5 gallon batch, and changed some of the hops. I lowered the grain amount slightly as I didn't want it at 6% (it was meant to be for the upcoming tennis club christmas do so didn't want everyone only going with one or two ) What's the best way of going about a half batch from a 5 gallon one please?

Nevermind, my math was not correct. Your recipe was good.

With a good crush and proper volume measurement, you should have gotten 1.055. But your batch was very far off. Based on @grampamark 's comment above, that would explain part of it, but you most certainly also must have either had a very bad crush or otherwise somehow did not convert or collect all the sugars adequately. Could be a sparge problem, could be bad pH, could be a lot of things. But I think it's definitely a combination of volumes and something else.

Yeah... pH was probably a little high, that might have hurt it, but the effect there is slight.

Overall I think it's primarily a crush and volume problem most likely.

 

[Frodo]

I would invest in a malt mill if I were you, or only purchase the amount of crushed grain that you need for a certain recipe, and brew with it soon after you buy it.

 

[howard86]

Sorry, being in the UK means most of the replies come during the night here.

I used a calculator for the amounts of water - https://www.the-home-brew-shop.co.uk/acatalog/Sparge-Water-Calculator.html

@grampamark Being in the uk, our litres and gallons aren't the same amounts as in the usa. But I got the amount of wort that the calculator suggested with the amount of sparge water. There was a little left in the tun after but with the valve opened to full no more could come out. Here the mash water was 1.46gallons, and sparge 2.83.I got a total of around 13 litres to boil. or 2.8 gallons which is still a little low I suppose?

@TurnipGreen I don't have a sparge arm yet, it's on the to make list, so I did the whole pouring water from a jug over the back of one of the big plastic brewing spoons method. But as said before, when I did batch sparging the SG was crazy off it's target too.

I'm going to get some malt for the weekend and see how that turns out in comparison. As well as a ph measure. Gypsum is what I need for increasing the acidity? I've seen that mentioned, but someone here said bicarb, which I thought reduces the acidity (certainly is good for getting rid of acid reflux anyway).
Cheers

 

[dmtaylor]

There was a little left in the tun after but with the valve opened to full no more could come out. Here the mash water was 1.46gallons, and sparge 2.83.I got a total of around 13 litres to boil. or 2.8 gallons which is still a little low I suppose?

Aha... this is the point at which you would have benefited from raking the surface of the grain bed. This is a common occurrence where fine particles settle on the top of the grain bed and prevent proper drainage. So you lost a LOT of good wort due to poor drainage. If you just scratch the top surface a bit, suddenly the flow should return and you'll not lose all that good wort. This also explains your low pre-boil volume.

Yes that's the main problem.

Gypsum is what I need for increasing the acidity? I've seen that mentioned, but someone here said bicarb, which I thought reduces the acidity (certainly is good for getting rid of acid reflux anyway).

You're correct about that. Bicarbonate will increase pH and thus reduce acidity. And yes, gypsum will do the opposite.

Better luck next time.

 

[grampamark]

This place is so informative. Who knew the British had different liters?

 

[howard86]

@dmtaylor hmm, if that is the reason then I'd better try it on Friday which is my next brew day. Turns out I've got some gypsum stashed away in some bits and bobs I inherited so I'll try that as well and see if it makes a difference.

About the bit left in the tun, I've got one of those ice cube cooler box ones (inherited as well), with a bazooka filter attached to the valve. Even when I tilted it, some extra came out but when I chucked out the grains there was a little left. I don't see how I'd manage to get that out. Maybe its my tun or is one of those round ones with the false bottom filter better for that?

Scratching the top of the wort, is that just with the spoon? All the videos I've watched always said avoid disturbing the grain bed so I stayed away from poking at it. Thanks again

 

[dmtaylor]

About the bit left in the tun, I've got one of those ice cube cooler box ones (inherited as well), with a bazooka filter attached to the valve. Even when I tilted it, some extra came out but when I chucked out the grains there was a little left. I don't see how I'd manage to get that out. Maybe its my tun or is one of those round ones with the false bottom filter better for that?

Scratching the top of the wort, is that just with the spoon? All the videos I've watched always said avoid disturbing the grain bed so I stayed away from poking at it. Thanks again

I've used a similar mash tun. It's important to tilt the mash tun at the end to get as much out as you can. There will always be a little liquid left at the bottom when you clean it out, but if you can get about 95% of the liquid out then you are doing well enough.

Commercial mash tuns have rakes. Just saying. If flow is totally stopped, scratching the surface with a spoon or really anything at all should prove very helpful. You don't want to go too deep, just a very light raking, only a centimeter deep or so, that will help.

 

[howard86]

@dmtaylor thanks again for the advice. I've checked the water and it came up at 7.04 on the ph reader that I got, so when I do my next brew I'll add some gypsum to the mash water and do the raking idea you've suggested during sparging and see what happens. I'll post the outcome on here, should be Friday most likely

 

[dmtaylor]

...the raking idea you've suggested during sparging and see what happens. I'll post the outcome on here, should be Friday most likely

Only rake IF the runoff gets stuck. If the wort all runs through on its own then it's a little better to just not rake it. Just only if it gets stuck. A little raking for a couple of seconds might be all that is needed... or maybe not at all. Be gentle, I guess that's what I'm saying.

 

[howard86]

@dmtaylor sorry for the lateness in getting back about this. I brewed last Friday and had a colossal accident on saturday morning (dropped the 5 gallon carboy and it smashed). So today I brewed a 2.5 gallon batch.

I was brewing this tripel I'd found on the net that I had a go at earlier in the year

12lb Pilsner
2lb Caravienne
2lb cane sugar (I just used brewing sugar as I had a bag of it)
1oz Northern brewer @ 60 mins
1oz Mt Hood @ 15 mins
1oz Mt Hood @ 5mins

I had a starter of wyeast trappist high gravity #3787
Things to note - first brew, I bunged in about 100g of gypsum and tested the ph (the water is normally 7.06 give or take) and it didn't seem to lower it much.
SG was 1.072 ish (recipe suggested 1.087-95 or so) so again lower than it should have been.

The half batch came out at 1.070-2 ish again. I had used that 5.2ph stabilizer which now I've read is more or less useless.

So I'm stumped unless it is the grains that just aren't crushed enough but that'd be more or less all the grains I've purchased.

 

[dmtaylor]

Well what have you done differently? If pH and/or salt additions is the only thing you've played with, then you are still missing the point. I think your grains probably need to be crushed harder, and I think there are some volume issues to be dealt with. Both of these are more important than pH and water. Anyway, if you used 100g of gypsum in 5 gallons, that is WAY too much.

 

[Harleybrew32]

do you know your systems mash efficiency? also the recipe you have is it from someone else?
if your efficiency is say 70% and the original recipe efficiency is 80% your SG will be lower.
I am a newbie here so forgive me if i am jumping in, just trying to shine some light in a different direction.
cheers

 

[howard86]

I will look at getting a mill then to see as a lot of the grains husks are cracked open but not really crushed as such.

As for brew efficiency, I'm not entirely sure. I got my kettle, tun and cooler from a friend who's brother was an avid brewer but had passed on and they didn't have the need for it. The recipe was from here http://beersmith.com/Recipes2/recipe_102.htm and the posters efficiency is bound to be higher than mine

 

[Harleybrew32]

that recipe has a mash efficiency of 75% depending on your crush and sparge methods you could be close. when i was using a cooler and batch sparging i was closer to 70%.
here is a link for mash efficiency http://howtobrew.com/book/section-2/what-is-malted-grain/mash-efficiency
do you use brewing software? i used to just up my base malt some to get closer, you could also boil longer but your final volume could be less. sometimes DME is good to have on hand to cheat a little. might get in trouble for saying that.
cheers

 

[howard86]

I didn't take a gravity reading after sparging, but in previous cases I have and some usually come out about 1.037 though on the previous attempts at this tripel I think it was nearer 1.040.

I tend to always put the recipes into beersmith, but I'll do a test on the next brew to try to work out efficiency.

Having read up on some of the mills, unless we're talking crushing the grains so any husks are pretty much obliterated, they seem to do what I'm already getting when I've bought grains from the-home-brew-shop.co.uk and maltmiller websites.