Low mash efficiency

[Porky]

Hi
I have an interesting problem, I have bee brewing (all grain) for about 8 years and have made lots of different beers quite happily. Last year I suddenly found my sugar yield dropped dramatically. I had changed nothing, was using malt from the same supplier yet found my yield was down. I have since been checking every aspect of my brewing and can find nothing that would cause this. my method is once my equipment is prepared;
Heat mash water to 80C, add it to my mash tun. Check the water temp and when at 75C add my grain bill, check the temp of the grain bed is at 67C.
Mash for 90 mins. I have a double insulated mash tun and the temp only drops to 65C during the mash. Run of the wort. I batch sparge with a water temp around 80C to maintain a grain bed temp around 67C, sparge until I have my boil vol. Today I brewed from GW book Exe Vally spring ale which should have come out at 1048 but I only got 1030? My grain is stored in the dry and dark and is rotated regularly so is never old. Any ideas would be appreciated, as I say I have used this method since I began all grain brewing.

[Dave S]

Hi
I have an interesting problem, I have bee brewing (all grain) for about 8 years and have made lots of different beers quite happily. Last year I suddenly found my sugar yield dropped dramatically. I had changed nothing, was using malt from the same supplier yet found my yield was down. I have since been checking every aspect of my brewing and can find nothing that would cause this. my method is once my equipment is prepared;
Heat mash water to 80C, add it to my mash tun. Check the water temp and when at 75C add my grain bill, check the temp of the grain bed is at 67C.
Mash for 90 mins. I have a double insulated mash tun and the temp only drops to 65C during the mash. Run of the wort. I batch sparge with a water temp around 80C to maintain a grain bed temp around 67C, sparge until I have my boil vol. Today I brewed from GW book Exe Vally spring ale which should have come out at 1048 but I only got 1030? My grain is stored in the dry and dark and is rotated regularly so is never old. Any ideas would be appreciated, as I say I have used this method since I began all grain brewing.

It looks like your sparge water temp is a bit low - grain bed should be in the mid 70's, 75 - 76 ish. Mash pH can also have a bearing on extract efficiency. It should ideally be 5.5 at room temp.

[boingy]

There's nothing in your description that would explain such a sudden change. All I can think of is that your measuring equipment might be faulty. Check your weighing scales, your thermometer and your hydrometer.

What is your usual mash efficiency and what is it now?

[Porky]

I have checked my thermometer (digital) against 2 others (1 digital also) and these were consistant. I have checked my hydrometer as I have 2 and I borrowed another again consistant. I haven't check my scales, but I will, though I think to drop this far would be noticable in the volume of grain. I would normally expect to get around 70% efficiency and could normally expect to hit the OG as in GW book. I will try on my next brew raising the grain bed temp to the mid 70's as suggested.
Thanks guys (or girls) for your suggestions.

[boingy]

Raising the sparge temp and tweaking your mash pH is not going to get you another 18 gravity points.

I suggest you do a starch test at the end of your mash. That will at least tell you if you are getting a decent conversion.

Did you measure the gravity post boil (and with cooled wort) and did you end up with the target amount of wort in the FV?

Other than that I'm stumped. If you were a newbie then there are loads of other errors you could be making but to go from good success to less success without changing equipment, process or ingredients is a bit of a head scratcher.

[Hogarth]

Sounds mysterious. If you're doing nothing different then perhaps the grain HAS changed, even though it's from the same supplier. Dunno, just a thought. Could be worth getting a few kilos from someone else as an experiment. As Boingy says, I don't think it's to do with spargewater temp.

[Dave S]

Boingy is right. Although your sparge temp should be a lot higher, and it will make a difference, it's difficult to imagine it making 18 gravity points difference. The reason for the the sudden change has to be something more fundamental

[ivanmalley]

I'd be checking the grain crush size hasn't changed first.

Same grain with a coarser/finer crush can make a massive difference.

Do you mill your own grain? If not your supplier might have a new mill.

[Porky]

Your views are all interesting and appreciated. I will try raising the sparge temp, it can't do any harm to try a mid 70 temp. I will also try a starch test as I have never done this.

[guypettigrew]

If you're always doing what you've always done, with the same grain, then changing your sparge temperature won't get you your extra points of gravity.

Checking the crush of the grain is a good idea, but you're probably working your way through a sack, so the crush will be the same all the way through.

Your measuring gear is OK, so you're not getting any false readings.

There's a slight possibilty your water may have changed but, to be honest, it's so unlikely to have any real effect on your mash efficiency it can be disounted.

All we're left with is an inefficient sparge. Have you changed your sparge process, even slightly? Have you stopped stirring the grain between batch sparges--or started stirring the grain?

This is mash eficiency we're talking about, isn't it? Or is it OG in the FV? If the latter, perhaps you're losing gravity in the hops. Mad, but possible.

Can you think of anything, no matter how small, which has changed since you were getting the better efficiency?

Guy

[colgilbec]

Agree with all of the above, another possibility is your grain,you stated you rotate it, but is it a new batch?
A few including myself had a bad run on Bairds a while back and i was was initially at the same stage of frustration you have mentioned,till i did a back to back with another grain source,just a thought to help you.

[Martin G]

What about the boil? Wonder if something minor like a lid or element change has lead to less boil off? Or water volume measurement? I guess they would have to be pretty noticable to make that much difference though.

[smdjoachim]

Have you calibrated your scales,hydrometer etc?
Has the water changed ?

[jonnyt]

You must be brewing on the moon, that's the only logical explanation.

[alix101]

I had read an article that the barley crop was poor last year. it could be a combination of a poor crop and a poor malting resulting in low sugar content...
My efficiency has been down on certain malts...