DO Readings

[Brody]

Today I got a chance to audit my process. As I've mentioned before, I brew outside, on propane, BIAB, in a Blichman Boilermaker. My obvious concern in implementing low-DO processes is the BIAB/Single Vessel mash in and lautering. I figured I'd put it to the test.

Strike Water: I hit the strike water the some sugar and bread yeast and let it sit in the 80s for a couple hours while I ran out to the shop, scooped up propane, and ate. When I got home I hit it with some heat and took a reading 0.38ppm at 109f. I'd say that's pretty good, right?

During the mash: Dough in was a bit scary as always. Mixing the grain in and watching some float up. But the extech indicated it wasn't as bad as I thought. My readings during the mash fluctuated in the high 0.8's peaking at 0.95ppm. Also pretty good, right?

After the lauter: I cringed as I pulled the bag up and watched the wort drop and dribble into the kettle. When I was done I gave it a gentle stir and took a sample. 1.05ppm. Again, I was pleasantly surprised.

Unless anyone thinks my DO levels got high enough to do damage even with 100ppm SMS I suppose I'll stick with my current set-up. One of the biggest arguments against lo-DO brewing is how hard it's supposed to be. I think this illustrates further how far from the truth that is. I have a basic, single-vessel setup, didn't even pre-boil, and seem to have hit acceptable levels.

A side note - I have a bit of a beater batch on tap due to a zero water filter giving out on me. The short of it is once the filter goes bad it leaches back into the water the minerals it pulled out and I ended up with a hard instead of soft water helles that's not ideal. I figured why not experiment on it. After measuring 0.17-0.19ppm in the keg I popped the top and hit it with a pre-boiled gelatin solution. Measured again a couple days later. I don't have the exact reading recorded but it brought it up to ~0.5ppm... so not worth the clarity.

[wobdee]

Nice, thanks for sharing. Are you a bag squeezer or did you just let gravity do its thing?

[Brody]

[Big Monk]

I would think that due to the amount of oxygen you are picking up post scavenge, and the fact that from that point on you have no active protection (NaMeta), that you may be riding a razors edge.

Before ending NaMeta use altogether you may want to tighten up your system/process.

[Brody]

What do you mean by the amount of oxygen I'm picking up post scavenge?

I could be mistaken but under 1ppm throughout the hot-side doesn't seem out of line. Especially when you take into account that the readings will be higher than what is actually happening in the mash (due to having to pull a sample and take the time to cool it).

The figures seemed not far off from the readings posted by Russ in the "Alternate methods for oxygen scavenging mash water" thread. Honestly, I was surprised my readings weren't higher. Are you seeing significantly lower than 1ppm hotside?

I'm planning on sticking with the paper's SMS dosage for a while since I haven't noticed anything unpleasant with SMS use.

[Big Monk]

I'm just thinking that you are encroaching on the upper limit. It would be nice to know you have a fair bit of margin.

I'm not familiar with using the meter so I don't know about the delta from sample to actual so I may have jumped the gun.

I think I also misunderstood you as well. You're just replacing pre-boil with yeast scavenge, right? And still dosing with 100 mg/l of NaMeta?

I thought you had ditched NaMeta altogether.

[Brody]

Ah, yea - still using the 100ppm for sure.

The yeast & sugar idea I took from Bilsch. In my limited experience with it it's easier for me to implement and results in pretty low-DO strike water. Overnight works even better.

Easy things I can do to keep my levels lower without spending much $:
1) Let the yeast scavenge overnight.
2) Slightly increase the grain and water I mash with to limit any bag dripping time even further.
3) Consider underletting. I plan on trying this with my boilermaker and cooler to see if it results in much lower readings.

Then the question I would have for myself is how good is SMS? Is it powerful enough that the differences between a hot side peaking ~1ppm would be about the same as say <0.5ppm with a super tight system?

I think if I was a stable homeowner I'd invest in a nice system, I mean who's not jealous of Bryan's rig? Haha. But I'm glad to see that (again, unless I'm mistaken about my readings) a simple set-up is doing the trick pretty well.

[Techbrau]

Isn't it incredible how popping the keg lid open for a few seconds and tossing in a little gelatin brings you all the way up to 0.5 ppm?

By the sound of it your process is doing just fine. If at some point after tightening it up even more you start to notice a burnt match smell or too much sulfur, it means you can start reducing the SMB dose. At that point try throttling the SMB back to 60-70 or even 50 mg/l. If you have the sulfite test strips, you can measure your post boil wort - I like to see about 20 ppm sulfite left over in the cooled wort, which I can achieve nowadays with an initial dose of 50 mg/l SMB.

[Brody]

[Big Monk]

I didn't mean to imply that there is anything wrong with what you're doing Brody.

I just work in an industry (commercial nuclear) that holds margin in high regard.