This is my first post in the forum. Thank you very much to those who want help me and sorry for (I guess) some mistakes in "my English".
I started brewing a bit more than a year ago and the four first times I got beer, as I expected, ones better than others. The forth time I had a "great" idea: a friend of mine has a factory of cure meat and I thought I could leave a secundary fermenter for a couple of weeks in a refrigerating chamber of his factory at 32 -35 ºF, in order to get a very clear beer. I got it, perfectly clear.
But from that moment on I've just been getting contaminated beer (I think for nine or ten times). I've cleaned everything carefully, using even NaOH solution and rinsing with a mix of acetic acid and hidrogen peroxide, including heat treatment (p.e. I put the chiller, valves and silicone pipes in a oven for 36 hours at 250 ºF), replacing fermenters by new ones, replacing airlocks by blow-off tube... Last time I bought a ozonizer (not high quality, 400 mg/h) and tried to "clean" the place where I brew: 1 hour per day for 7 days in a row, but always the allien wake up and get inside my beer.
What kind of contamination? I'm not sure, but it's something hard-sour, specially in the nose. It begins at the beginning of the fermentation, I mean, even the day after the brewday I can smell it. Also I can see a white foam at the top of the fermenter.
Why I say a "great" idea, with reference to the two weeks in the refrigerating chamber? Because in that kind of chamber there are lot of bacterias. I suppose that some bacterias set in the surface of the fermenter. Because the airlock, those bacterias couldn't get into the fermenter, but survived outside and settled the brew place. So they are in the air. It's just a supposition.
I oxigenate saking the fermenter, just before pitching the yeast. Maybe I could improve the procedure using oxigene, but I saked the four first times and I hadn't got any problem.
Have you got an idea to solve this situation? I'd be very pleasant if you can help me. Thank you very much.