Significantly missing OG with RIMS system

[lititzbrew]

Hello,

First time user here so excuse me if I make any homebrewtalk faux pas.

I've got sort of a frustrating issue with my RIMS setup that I need some advice on. I finished building my system about 2 months ago and since then I've brewed 6 batches using it. I've tried several different styles and each time it seems to be the same story: I miss my OG by A LOT.

I'm perplexed because each time I nail my mash, sparge, boil, volumes, etc... Yesterday I made a 10 gal batch of Imperial Pale Ale with an estimated OG of 1.077. There was about 28 pounds of grain (mostly 2 row, Vienna, Munich), added 9.5 gal of water and doughed in, set the RIMS system to 154F, and let it recirc for a 60 minute mash. After the mash I took a gravity reading at 1.060. Without mashing out, I transferred the wort to the Boil Kettle and proceeded to sparge. I batch sparge in 2 steps using 168F water, stir, then let sit for 15 minutes, in this case I used about 2 gallons for the first sparge, then 7.5 gallons for the second. After sparging I took another gravity reading at 1.054 (estimated 1.057), so I was a little off but nothing I was too concerned about because of the temp offsets. I then boiled for 90 minutes, evaporated down to 10 gal, ran the wort through the plate chiller until I got down to 70F and took another gravity sample before pitching and, believe it or not, I got a reading of 1.052 So, not only was I 23 points off my mark, I was also below my pre-boil OG which is scientifically impossible, right?

This was actually the first time I took gravity readings throughout the entire process, but the OG for every batch I've made seems to be around 1.050 to 1.055. I make adjustments every time, and was pretty sure I was going to nail yesterdays batch, but now I'm confused on where to go from here. I calibrated my Hydrometer and it's a little off (+1 or 2) but not enough to make a huge difference.

Am I not doughing in enough? I try to be gentle when doughing in so that I don't disturb the false bottom and end up with a stuck mash/nightmare. I also noticed when cleaning out the grains yesterday that some of it was stuck together like mashed potatoes. Is that normal?

After doughing in should I let the grain bed settle for an extended period of time?

Should I be mashing out? I've mashed out before but I've read conflicting views on this. Would it make a huge difference in my efficiency?

Could I be taking bad reading with my hydrometer? I understand temperature has an effect on the readings, but I take that in to account so maybe it's just a bad sample?

Bad crush? I get my grains crushed at the local home brew store, and to me it looks decent. I wouldn't think my efficiency would be so low just because of a bad crush or would it?

I use BeerSmith for my water volume calcs. I account for dead space and always seems to be spot on with the finished volume, but maybe I'm missing something.

I just don't understand where I'm going wrong here. It's so frustrating that it's all I've been thinking about for the past 24 hours! Any help here would be greatly appreciated!

Tom

 

[Tupperwolf]

Are you taking all of your hydrometer readings at the same temperature (usually 60*F calibration)?

 

[acidrain]

With 9.5 gal. of water plus your grains, are the grains completely covered with a bit of water on top?
When recirculating, is the return water introduced onto the top bit of water gently, or is it channeling into the grain?
I use a direct-fired + RMS too, and have noticed that a little thinner mash so that a significant amount of water is above the grain bed, plus introducing the return water onto that water so that it makes a slow circling motion results in better efficiency. Some guys use a pan with holes to evenly distribute the return water onto the grains.
The other thought is the actual vs. measured mash temp. Have you calibrated your thermometer, and do you measure many locations of the mash?
What about the hydrometer reading. It sounds like you measured at elevated temperatures, and then adjusted per temp. The most accurate reading is at whatever your hydrometer is calibrated at (usually 68F, but sometimes 60F).

 

[lititzbrew]

Are you taking all of your hydrometer readings at the same temperature (usually 60*F calibration)?

I try to, but sometimes I'm a little off so I usually take the temp and plug it in to the Hydrometer Temp Adjustment Calculator. I know I'm not far off.

With 9.5 gal. of water plus your grains, are the grains completely covered with a bit of water on top?
When recirculating, is the return water introduced onto the top bit of water gently, or is it channeling into the grain?
I use a direct-fired + RMS too, and have noticed that a little thinner mash so that a significant amount of water is above the grain bed, plus introducing the return water onto that water so that it makes a slow circling motion results in better efficiency. Some guys use a pan with holes to evenly distribute the return water onto the grains.
The other thought is the actual vs. measured mash temp. Have you calibrated your thermometer, and do you measure many locations of the mash?
What about the hydrometer reading. It sounds like you measured at elevated temperatures, and then adjusted per temp. The most accurate reading is at whatever your hydrometer is calibrated at (usually 68F, but sometimes 60F).

Yes, the grains were always completely covered with at least 2 inches of water above the bed. When recirculating, there is a little bit of grain floating on top and I only assume the grain bed is settled during the mash.

Interesting point about evenly distributing the water on to the grains. I think I will try a few of your methods during my next session. I've previously been afraid to restrict the flow because I use an electric element and didn't want to burn it out. I just got an ULD LimeLife element so I should be good now.

I've tested my thermometer multiple times. I measure the top of my bed and sometimes it's almost 2F cooler than what it's set for but I usually just raise my set point by a degree.

What do you think about mashing with more water and sparging with less? 90 minute mash with 12 gal +\- of water and sparge twice with the remaining water?

 

[acidrain]

My efficiency is a little low too. I've brought it up a little by making sure I'm recirculating through all the grains, but still a little lower than when I was doing BIAB. I'm going to experiment with even thinner mashes.
I haven't tried mashing longer... iodine test showed that I'm getting full conversion in the first 1/2 hour, but the funny thing is when taking multiple refractometer readings, the gravity continued going up and then leveled off at about 1 hour. I've read you really can't trust an iodine test, so I don't know what to think.
I'm going to try thinner mashes first, and then maybe longer mashes after that. I don't want to try more than one thing at a time.
Thinking about multi-step mashing too.

 

[isleofman]

By a little off in your hydro samples, do you mean you are adjusting from a wort sample @ 150F or 75F? Once you get so far off from the calibration temp, the equations don't scale.

 

[lititzbrew]

My efficiency is a little low too. I've brought it up a little by making sure I'm recirculating through all the grains, but still a little lower than when I was doing BIAB. I'm going to experiment with even thinner mashes.
I haven't tried mashing longer... iodine test showed that I'm getting full conversion in the first 1/2 hour, but the funny thing is when taking multiple refractometer readings, the gravity continued going up and then leveled off at about 1 hour. I've read you really can't trust an iodine test, so I don't know what to think.
I'm going to try thinner mashes first, and then maybe longer mashes after that. I don't want to try more than one thing at a time.
Thinking about multi-step mashing too.

Good to know I'm not the only one. Are you using a RIMS setup? I think I'm gonna try to do the multi-step as well. The guy at the my local home breq store said I should try mashing at 148F for 30 minutes then at 161 for 30. I guess it has to do with the alpha and beta enzymes which I'm still starting to understand. I hear and read so much that I don't know what to do but, like you, I only want to do one thing at a time to see what works. On to the next experiment.

Thanks for the feedback.

Cheers.

 

[pabloj13]

Something's not right here. Your OG can't go down after the boil off. One of those two numbers is wrong.

 

[Bordy]

Try using a glass hydrometer maybe. Temperature also is big.

 

[acidrain]

Something's not right here. Your OG can't go down after the boil off. One of those two numbers is wrong.

I went back and re-read your OP... pablo is right. You probably didn't mix well when you added the sparge to the first running before the gravity reading, but, you probably did get an accurate gravity reading after the boil. That doesn't make things any better, does it?

Yes, I'm running a RMS. I'm direct fired, bottom draining, and after I dough-in and settle, I start the RMS. I'm hitting a consistent 75% brew house efficiency, and I've begun to bump up my recipes to get my gravities using BeerSmith.

 

[SavoryChef]

Sounds like a crappy crush to me. .I get 85% efficiency with my Rims, and my gravity readings are 1.090+ on my first runnings with 1.25 qt/lbs and .33 gallon deadspace.

 

[lititzbrew]

Just got a Barley Crusher and a second hydrometer. I'm going to do a coarse crush and I think that was my main issue. Rice Hulls helped but I'm still not happy with 70%. I'm brewing on Saturday and will report back.

 

[opiate82]

There was a pretty good write up on RIMS efficiency over at Brew-Magic's blog. Maybe some of the tips there can help you out. LINK

 

[lititzbrew]

Last Saturday I brewed and crushed my own grains using my new barley crusher. I set the gap slightly wider than the default setting. I ended up over-shooting my OG by 0.003 and an estimated mash efficiency of 92%, according to Beer Smith! Thanks for the advice, everyone. I can now sleep peacefully at night! Cheers.

 

[SavoryChef]

Sweet!!