Awesome new Mash Tun - Not so awesome mash efficiency!!

[Dan]

Ive previously been doing my  mashing in my 16L boiling pot.  Could squeeze 4.5kg grain in there , do the mash at 67deg then pour it into a bucket of sparge water at 75deg and use a voile bag to "dunk sparge". System worked well and could consistently get about 65% mash eff this way.

Decided it was time to treat myself and splashed out on a 38L rubbermaid with s/s false bottom and tap from Morebeer. (see pic)Did my first brew yesterday with it , a Pilsner using 90% Malteurop Pale and 5/5 % carapils/ Carahell. Did a 75min mash at 67, using 13.5L  water (water to grist at about 3.4). and 1/2 tsp of gypsum.  Re-circed and lautered then batch sparged using about 8L of water at75deg, let sparge water sit for about 15mins then slowly drained it over about 10mins.

Total wort gathered was 13L (for my 16L pot) but efficiency was only 57%!!!! Man I was disappointed as was hoping for better than 65%!! My grains were ground the same way as usual and water etc exactly the same (Te -marua supply with gyp added)

I know a few guys on here have got one of these to and was hoping for a little advise on what they do and what efficiencies they get.   Any comments gladly received as I want to do better on my next one in a few weeks time!! Cheers

[Stu H]

Hey Dan,

That looks like a sweet piece of kit. I recently moved from a bag type setup to a (less tech) traditional mash/sparge setup, and found I had efficiency losses too. Check out the advice here, some of it should be relevant.

 http://www.forum.realbeer.co.nz/forum/topics/mash-tun-woes

I found that with batch sparging you've got to pay attention to the volumes you're using heaps - try and keep the collections from the mash and sparges equal in volume. I usually try for a 10L collection from the mash, and 2x 10 litre sparges...

I suggest also brewing a few inexpensive low gravity bitters or something, with the same grists, and experimenting with your crush, sparges etc. It'll take a few brews but you'll get there.

[MrC]

How much dead space do you have in that cooler?  When doing small batches on a system designed for bigger batches the effect of dead space on efficiency is exaggerated.

Also, I think your second run-off may have been too small.  Try it again but keep the run-offs of  equal size.  You may need to mash thicker but it will help rinse the sugars out more effectively with the second run-off.

[JackoNZ]

Hey Dan, I've got the same cooler you have there. I used to do BIAB at around 65% brewhouse efficiency. I thought I'd get a lot more than that with the cooler but I plan for 70% these days. I fly sparge rather than batch and found it took a couple of brews to get the mash/sparge sorted. I think I could go higher if I played with the ph of my mash but haven't got into the salts yet. I usually extract around 80 to 85% from the grains which I'm happy with. 

If I've done the numbers right it looks like your grain bill was about 4kg? If so I think you didn't get as much wort out of the mash tun as you could have. My cooler has a dead space of 1.6L so I'd be expecting to you to get a couple of extra litres out there at least. As the guys above have already mentioned I believe the batch size should be as close to equal size as possible too.

[Grant R Baker]

Couple of pointers...

Make sure you have a 2.6 ratio of water to mash for the strike (that's litres to kilos) and the reast (hoperfully at least a 2.0 ratio) for the batch sparge.

Ensure your mash is at the temp required. The grains will cool your water and I lose 2C degrees when transferring hot water from the boiler to the mashtun. So 67C desired mash is about 77C in the boiler for me (depending on how cold the day is). Your brewing software should help calculate that.... but if not keep a 2L of boiling water that you can top up the mashtun with to hit your temp. (just remove the 2L from the batch water).

Lastly - times, 60-90 mins for a mash, then 30mins for a batch sparge.... really big brews require longer batch sparges.

Try not to think of it in fly-sparge terms where you sparge until efficiency is reach.. but were you mash & sparge long enough to reach it.

[Dan]

Thanks for the tips guys, lots of ideas to try here. Let you know how it goes in a few weeks! Cheers

[Kelly Milligan]

Hey mate, I've got a rubbermaid cooler with false bottom too and the biggest thing I've found to affect my efficiency with it is run-off rate. My efficiency will seem to vary between 70% and 85% depending on how slow I run off. Sometimes I'll take a full 30+ mins just to run off my first runnings, then start heating while I run in the sparge. Seems to work for me and I'm getting much clearer wort into the kettle that way too :)  

[Liam Callaghan]

I was going to ask pretty much the same question this morning, thankfully the answers may be here! 

Seems I run a pretty stiff mash though when Tom had a look at it yesterday but I have always run it like that and usually get around 80%.  Grain was totally spent though from what I could taste.  4.5kg pils, 1.25kg munich and 0.25kg wheat for 1.044.  Gutted at 70% so I ran it again with the exact same result :(

Might be time for a brewing party with some of you clever people and see if we can rework it back to its former glory!

[Grant R Baker]

Maybe just drop your attenuation to 75% in the brewing software.. thus if you want higher ABV you just have to add more grain.

 

I read somewhere that pH level of the water effects this too... but I have found a longer mash = better attenuation.

[Gareth Kerr]

We use pretty much exactly the same setup as you for the mash tun, and also had some efficiency problems when we first started using it, only managing around 60% for the first couple of brews. We're now getting 80-85 extraction after doing a few things differently, but given we made so many changes it's hard to pinpoint exactly what made the difference.

I suspect the biggest for us was probably the crush of the grist. After doing some reading around the consensus seems to be "reduce the mill gap until you're scared, then back off a little", and having a bit of flour (5% or so) isn't a problem. I'm not sure if you mill your own grain but if so, it could be worth a try to adjust the gap down a little.

We also added some acid malt to reduce the pH to around 5 or just over. It wasn't outrageously high to begin with, but it may have made a difference. We were also a bit lax about stirring the mash sometimes, so now try to make an effort to give it a good stir up every 15 mins or so. Runoff speed seems to make a fair bit of difference with these too, although we've found it can be tough to get a consistent flow at a slow rate sometimes.

As some have said, 13L gathered from 21.5L also seems a little low, so maybe your runoffs need looking at too.

Good luck, I'm sure it'll come good for you in time!