Stop Fermentation. Please help!

My primary has just finished its tenth day and appears to have stopped fermenting (no bubbles in the airlock for the past 3 days). I used White Labs California Ale V and pitched it right out of the bottle. It called for fermenting temps between 70 and 75F (I've been keeping it at 72F) and has an attenuation of 70-75%. I took the first gravity reading yesterday and yielded only an attenuation of 57%. I added 1kg of sugar to the boil (6 gal) so there should be plenty of fermentables left. My aeration was a little weak and it took about 15 hours for the wort to cool to pitching temperatures (Possibly allowing infection). When I tested the beer it tasted a little sweet but other than that there were no other off-flavors. If fermentation has stopped short, what might other possible sources of error have been and how do I still get a good beer out of what I've got?

Give it a shake.

What was the OG what is the SG now?
What was the recipe.

1 Can John Bull Pilsner Pre Hopped Malt Extract
1Kg Corn Sugar
Both added to 6 Gallon Boil
Cooled to 75F before White Labs Ale Yeast V added (Subbed for kit dry yeast)

OG: 1042 SG:1019

Maybe I should add more yeast?

What is it with these kits recommending adding so much dextrose to such weak beers? Just seems wrong to me, and also like something that will discourage further brewing due to poor results.

Back to the subject: I don't think adding more yeast would necessarily help. You could swirl it around a bit and see if it gets going again, and then wait a few days. If you don't get any more action in the next few days, you could consider adding a packet of a dry yeast like Nottingham to finish things up.

I shook my primary vigorously yesterday and fermentation resumed today! Thanks for the tip guys.

Torchiest said:

What is it with these kits recommending adding so much dextrose to such weak beers? Just seems wrong to me, and also like something that will discourage further brewing due to poor results.

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I've always wondered the same thing. Couple of ideas:

Corn sugar is easier to stock. Lasts forever on the shelf unlike malt extracts

Many people brew to make an alcoholic beverage. Taste is secondary

Thinking that by adding a lot of dextrose, fermentations will be guaranteed (I've read that this can be the opposite. High levels of dextrose in the wort can inhibit fermentation.)

Shops that primarily sell wine making supplies and don't know jack about beer.

And lastly, dextrose is cheap. Malt extract is not. Higher profit margins.

Originally Posted by Torchiest
What is it with these kits recommending adding so much dextrose to such weak beers? Just seems wrong to me, and also like something that will discourage further brewing due to poor results.

Click to expand...

Because they don't give a crap about the quality of the product they sell or they do but they cater for customers that don't or are uneducated in the art of making good beer.