Last March I started adventuring into the world of Sourdoughs by following the advise of The Fresh Loaf Bakers's handbook but using wholegrain rye flour all the way and it went pretty well; after a week or so I started having nice sour rye breads. For context, this was a typical spring in Mallorca, known for its usual high humidity, with temperatures at home between 18-20ºC to about 30ºC by the time I left.
Then, I moved to Vigo (northwestern Spain) in the middle of July and sure shortly after I decided to make a new sourdough from scratch following the same recipe, but this time no orange juice.
For context, I set up a humidity/temperature sensor and got some values ranging 70% and 99% (crazy weather here) and intense 29-32ºC at home. The result was a rather smelly (and not in a good sense, nowhere similar to what I had before) sourdough after a few days, which after four or five days developed a thin white layer of something I thought would be mold.
I had searched for this at the time and found it might be mold, so I discarded it. Then I said to myself, it must be the orange juice, so I went and tried again with orange juice only to obtain the same results. This experimentation process went for about 4 cycles.
I tried feeding it twice a day, I changed the jar in which I was keeping it, I covered the jar, I uncovered the jar, I sealed the jar, all to no avail. By then I decided not to waste more time and wait for colder climate maybe (haven't done so yet, though).
Now I'm thinking I want to start again, but I'd like to get some feedback from more experienced users into what might had gone wrong. I even started to suspect it was related to the quality of water (which I purify with one of this Britta filters, any thoughts?) or of the air.
For reference: my sourdough would get a layer, not as bad, but close enough, to this: The Fresh Loaf post