My last batch made me paranoid about developing off-flavors in my beer. I made an American wheat and due to the summer heat, the fermentation temps got up to the mid 70's. It's sitting in the keg now and I can sense a bit of weird flavors that I'm hoping go away soon. For my current batch, I made sure to control my temps from the very beginning. I didn't have any luck last time with the traditional swamp cooler and t-shirt method, so this time I just put my better bottle in a big rubbermaid container and filled it with water so it's right around the level of my wort. I'm able to keep the temps of the water between 60-65 by swapping frozen water bottles, and my fermometer reads between 64-68, although it recently started turning all different colors due to being submerged. I'm actually surprised it was able to maintain effectiveness while being wet for this long (two and a half weeks so far). My question is, does this method suffice, or do I need to get a temp controller? Is this minor variance in temperature detrimental to my beer? I tried to test out my spare fridge temps a few weeks ago by filling a carboy with water and setting the refrigerator temp to the lowest factory setting (warmest setting) and my fermometer still read about mid 50's. Since this is too cold for ales, will a temp controller solve this, or does my fridge actually have to get warm enough for a temp controller to be effective?
Thanks for the help.