Seeding tray after poor fermentation

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New Member
May 9, 2022
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First time brewer here.

I've started my first ever homebrew (Wilko's Red Devil Ale) and noticed that I haven't been getting much activity from my airlock. There has been a constant pressure on it, but not enough to make it bubble over.

I took the lid off the bucket on day 5 to add my hops and noticed that it was definitely bubbling/reacting.

I've been keeping track of the temperature and I've only been able to keep it between 16-18 degrees, which the instructions say should be fine but I'm unsure as I've read elsewhere that it's supposed to be between 20-25 degrees.

I was wondering if I would ruin the brew by placing a seedling heat mat under it now and bringing it up to 20 degrees?

Thanks for any advice.


Supporting Member
HBT Supporter
Nov 26, 2010
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Bucket lids are notorious for leaking. Your airlock shows that there is pressure so you know something is happening but it only takes a little leak around the lid to let out the CO2 before the airlock bubbles. It doesn't really matter, the airlock is there to keep insects and bacteria out while allowing excess pressure to be relieved before the pressure blows the lid off the bucket, painting the walls, ceiling, and floors with krausen.

Your temperature is perfect for the start of the fermentation as keeping the beer cool while the yeast are very active will avoid the off flavors that a warmer fermentation will get you. Once the activity slows down, often on day 4 or 5, it is a good practice to warm the beer so the yeast complete fermentation and consume the intermediate products. I usually wait until day 7 to do so but a bit earlier would be OK. I keep the temperature at 22C until bottling time (10 to 30 days from pitching yeast) and then keep the bottles at that temp for at least 3 weeks to allow carbonation and the heading compounds to be produced before chilling for drinking. You may see haze in the beer from proteins unless you leave the beer chilled for 2 to 3 days.


Opinionated Newb
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Mar 10, 2021
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Airlock bubbles only have entertainment value.

You need a hydrometer to tell for certain if something is happening and when it's really finished.

Otherwise, just patience and time.

I usually ferment all the ales I do at 69°F or ≈20°C. But others do use lower temps. Which will be slower fermenting but might produce fewer yeast flavors if you are not wanting the flavors some yeasts impart.

As for warming it up, I'd probably put the heat mat around it. And run it on a low setting if you have a choice. And also use a temperature controller to turn it off when things get to temp.

I use one of these....