Foam and airlock

I have just started brewing for my first time and have one of these all in one starter kits see here (lager)

The instructions were not terribly clear or I misread (more likely) and didn't realise I needed to add the bubbler airlock to the top of my tub after I mixed everything together.

I'm into day 4 of fermenting now and have just added the airlock with water in. I have read you don't necessarily need an airlock but most people use them as an insurance, and I'm hoping I'm not too late in the stage to add it.

Also, I have noticed a small layer of foamy throth forming on the top of the brew in my container, is this normal? The instructions with the kit mentioned small bubbles will cease to rise after 4-6 days but I can't tell if its actually bubbling or not because of this foam layer, or do they mean bubbles ceasing to rise in the airlock?

So I'm just really needing advice, on what I should do next please. I don't want to bother kegging if I have screwed this up and should just start over.

Also, I have my setup in my garage right now, and temperature is reading at 18 °C so probably a little on the cool side?

Topic airlock foam homebrew

Category Mac

1
answered at

Airlock: indeed, you do not need it for the fermenting process, it is added as a way to insulate your brew from the surrounding air, to make sure that no contamination happens, and to remove the CO2 once your fermentation is under way.

  • Contamination:
    • moulds, spores and bacteria could enter your beer. I suppose you did add the lid, so that only the bunghole was open?
    • My personal experience is that, unless you keep your fermentation really open the whole time, the chance of contamination is low.
  • Fermentation: the yeast turns the sugars into alcohol and CO2, much CO2. So once this is going it will blow everything out and the chance of contamination gets much lower.

Foam and froth: the same mechanism that makes a head on beer also works when the fermentation is going on. The yeast blows little bubbles, and additionally also secretes other compositions, which make that a fermentation always has (sometimes much, sometimes less) foam on top of it.

One thing that is very confusing for starting home brewers is always: when is it finished? The short answer is: you should measure it. However, that is easier said than done, because you need to take a sample for that, so that you can measure the gravity with your hydrometer, and you should take that sample as quick as possible to avoid contamination.

An easier option is to let it ferment out for two to three weeks before bottling.

Temperature: I couldn't find out from the supplier if the supplied yeast is a lager yeast or another one, for this kit. If it is really a lager yeast (what is called bottom fermenting), then 18° C could be on the warm side. If it is a top fermenting yeast, then 18° is a nice temperature, especially in the beginning of the fermentation. In that case, move it now to a warmer place so that the yeast has a bit more support to ferment out the brew.

Also, when the yeast starts fermenting, the process also increases the temperature, so while your garage could be 18°, the inside of the fermenter could be 20° to 22°.

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