Vorlauf and air bubbles

Hi,

Did an AG last weekend using a cooler as my MLT. While doing vorlauf I had trouble with air bubles in the 1/2" tubing. The bubbles rise up in the tubing to the MLT and mess up the grain bed. Everytime I close the ball valve and poor the vorlauf back in the MLT it starts all over again. Tried raising the tubing and let it fill up and then drop it slowly down, but there is always a little air.

What do you use to prevent this rising air.

I dont close the ball valve. If you just raise the hose to a level higher than the valve, the flow will stop and the wort will stay close to the end of the hose pretty much eliminating the possibility of air getting into the line. Also, keep the flow out of the valve slow.

I dont use a tube from my valve to the pot. I just open the valve. HSA be damned.

As lowlife mentioned, I also don't use a tube, I just open it up and let-r rip

+1 on no tube.

Will give the no tube a try on my next batch.

no tube?how are you supposed to get a siphon?
without a siphon your leaving precious wort absorbed in your grains.

Vorlauf is more of a drain than a siphon. Either with a false bottom or a manifold to screen the grain bed. By running lots of water through the grains, you essentially pull as much fermentable sugars (wort) out of the grain as you can.

Does the splashing of the wort into the kettle cause any hot water aeration off flavors? I have been struggling with a lot of bubbles being formed where the tube attaches to the barb coming out of the mash tun. I have been wondering if this is contributing to an astringent type flavor on some of my beers.

Astringency is usually caused by shredded husks, high pH mashes, or high temps during the mash/sparge. Oxidation causes sherry and cardboard/paper flavors. It is however questionable how much of an effect HSA has for bottle conditioned beers. Check out the Brew Strong podcast on HSA.

dmaher said:

Does the splashing of the wort into the kettle cause any hot water aeration off flavors?

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No, aeration at this point is not bad. After the yeast is added to the beer, THEN splashing and aeration is a bad mojo.

IXVolt said:

No, aeration at this point is not bad. After the yeast is added to the beer, THEN splashing and aeration is a bad mojo.

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I don't think anyone is actually that certain on this point. Oxidation can cause off flavors but usually the yeast does a pretty good job of cleaning it up. It is potentially a problem when the wort is hot, and after fermentation has started to subside.

Joos said:

no tube?how are you supposed to get a siphon?
without a siphon your leaving precious wort absorbed in your grains.

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I guess it all depends on mash tun design. If I didn't have tubing on my spigot from the mash tun I'd leave about 1.5 inches of wort in the bottom of the tun because I wouldn't have a siphon to pull it up through the valve. If your drain hole is on the bottom of the mash tun then you wouldn't need to worry about that (Which is what I did with my boil pot).

IXVolt said:

No, aeration at this point is not bad. After the yeast is added to the beer, THEN splashing and aeration is a bad mojo.

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Aeration during wort transfer is not a good thing, but it probably won't cause any issues, especially if it is a beer that won't age a really long time. Oxidation affects take a while to show up. However larger breweries have had issues with oxidation during transfer to the boil kettle, as a homebrewer though we don't need to worry about it, our transfers are not nearly as violent as theirs (wort falling 10ft to the bottom of huge kettles etc.)

THere are a lot of weird statements in this thread. I'm not saying they are wrong but they are against most accepted brewing wisdom. First, running a piece of tubing off the MLT drain is the usual to keep a nice siphon going. It's rare to have the separation medium and bulkhead at the dead low spot of the tun. No output tube means more deadspace in 90% of tun designs.

Even though hot side aeration is unlikely to be a problem, there's no reason to splash hot wort when you can easily avoid it.

If I didn't use a tube attached to my MLT, the flies would drink all the wort.

If you are drainig your MLT into your brew kettle to boil, aren't you removing any oxygen from the wort via boiling?

In essence elimantaing any HSA from MLT wort transfer?

Schnitzengiggle said:

If you are drainig your MLT into your brew kettle to boil, aren't you removing any oxygen from the wort via boiling?

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In theory. However, the principle of HSA is that the oxygen binds to the hot wort, which is not boiled out. Here's some easy to understand info: Hot Side Aeration and Beer Stability
http://***********/stories/techniqu...66-hot-side-aeration-a-storing-hops-mr-wizard

Because the wort is hot, there are substances that are oxidized very quickly once oxygen starts getting mixed in. Boiling will remove the oxygen but it won't do anything about the substances that were oxidized during the transfer before the boil started.

What the hell is a vorlauf.

Grinder12000 said:

What the hell is a vorlauf.

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Catching a certain amount of the runoff from the MLT and adding it back into the MLT. This helps husks settle and filter better, and mixes the mash for better efficiency.

YooperBrew said:

In theory. However, the principle of HSA is that the oxygen binds to the hot wort, which is not boiled out. Here's some easy to understand info: Hot Side Aeration and Beer Stability
Brew Your Own: The How-To Homebrew Beer Magazine - Techniques - Hot-Side Aeration & Storing Hops: Mr. Wizard

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Point taken, I will soon (maybe a month or two) brew my first AG batch, and I am trying to understand all of this information before hand. Thank you for pointing out the error in my thought process.