(old) Starter lost its mojo
Hello. I have been keeping a starter for about a few months now. Since I was unsure whether it was active enough, I asked a friend for a bit of hers, which is over 2 years old, which turned out to be way more active than mine. I've been feeding it 1:2:3 and it would rise more than twice as fast as my young one. I baked a couple of loaves with it and it was crazy. While I was fermenting my dough for a total of 7 hours with my original starter, with less than 5 hours I was getting clearly overproofed dough now. The strange thing is that after one week, the starter lost all of its potency. It is not dead, but it is now at the same level as the one I had already.
I live in Rio de Janeiro, Brazil, and have been keeping it at room temperature, which translates to 30C (86F), when measured with an infrared thermometer. I mantain 67% hydration. As for feeding, I was feeding it twice for the first few days, but might have slacked off later in the week. I think I have forgotten to feed it over 24h right before I noticed its decay in activity.
I have read that while the bacteria in the culture thrive at higher temperatures, such as 30C, the fungus prefers it under 26C. I have also read that UV light might damage the culture. I do not store it in direct sunlight, but it is very bright here.
Anyways, these were the possible sources of the problem I could think of. The strange thing is that it seemed to have no problem at all for a whole week.
I have frozen a bit while it was still booming, so I plan to thaw it and see if still is very active. This is why I am posting: I'd like to avoid losing its vigor again. Also, if possible, I'd like to revert this situation with the current culture.
Any thoughts on what might have caused this behavior?