Baffled by bubbling; what is the risk of infection?

[andbrew]

Hi

I did a quick search but couldn't find the answer to this:-
if the seal on my fermenter is tight but the air lock bubbles for a few hours (about 8 hrs/24) and then stops for a few hours (about 16hrs/24) and then restarts with the same pattern what is the risk of infection?
Info:-
Cascade PA
kit yeast
1 kg BE1
0.5 kg LDMalt
Using brew belt and according to thermo on side of fermenter it has always been between 19~25 (cascade say between 19~26) but I think it is dropping too cool at night. Doesn't start bubbling until mid afternoon and then stops after about 8 hrs. Put down Sun and took 36 hrs for any bubbling to start. This pattern has been repeated Tues ~ Fri. When not bubbling is it at risk of infection?
SG was unavailable as my hydrometer was broken (!) but bought new one yesterday and currently it is at about 1024. I guess it would have been about 1040 when I started.

I wanted to try brewing at this time of year (in Perth) as it could then condition over winter outside ready for drinking when summer arrives.

Thanks for your advice.

[homebrewer79]

I would say your risk is minimal (assuming your sanitising is efficient),the layer of co2 will protect the wort. I'd be more concerned about the fluctuating temps(and the kit used). Try not to let it jump around so much. Keeping it at 19 deg will do the world of good, so long as the yeast is viable. Take that heat belt off and have a home brew

[andbrew]

Thanks homebrewer 79. The irony is that anytime when it is bubbling away, the thermo is always showing about 24/25 and the belt is on. Anytime that I notice it is not bubbling the thermo is showing a lower temp , but still at least 19 (usually 19/20). Are these stick on thermometers very accurate? Yes, the fermenter was sterilizied (and rinsed afterwards) thoroughly with sodium percarbonate.

[rwh]

My guess is you have only a partial seal, so it's only when it's really going hard that you see gas coming out of the airlock. Take off the heat belt! 19 degrees is enough for any yeast, and you'll get heaps better beer at that temp. The stuck on thermos are fine, I've found them to be within a degree or so.

[andbrew]

Thanks. It stalled at 1024 for 2 days. Way too high for FG I guess. I've probably buggered it up but I unpopped the lid yesterday (on one side only), just enough to chuck in another yeast (Coopers this time), quickly resealed, and gently rocked it. It has bubbled ever since. I guess there is an oxidisation possiblity (probablility? ) but it didn't seem to be fermenting with the kit bohemian yeast. Still smells OK. Should I go ahead and bottle it when I get a steady FG or do you reckon it is a lost cause? My fermenter has a snap on lid and the seal seems fairly tight but when I 'weight' the edge of the lid with something heavy it does seem to bubble at more frequent intervals. Does any one else have a snap on lid fermenter. Should I just keep the edges weighted down? Thanks for your advice.

[homebrewer79]

I have a snap on lid fermenter and a screw top one and I think the snap on one is heaps better, if yours has a leak around the lid I think the only precaution I would be taking is to bottle when it's ready and not to leave it in there for weeks on end

[rwh]

Yeah, don't stress. It'll be fine. Just bottle when it's finished.