I want to brew a lager and we just got a new fridge so the old one is sitting in the basement. The problem is at the warmest setting brings the fridge only up to 42-44 degrees and I understand thats too cold for most lagers. I cant afford a thermostat for a while and was wondering what to expect if I froze multiple jugs of water and used these to keep the fridge cold? Has anyone used this and how steady did your temperature stay?