Share 'Pretty Green scum build up'

My Pretty Green 2nd edition blue/pink has a scum build up around the bottom that keeps getting worse and worse. I bought it brand new and it's only 4 or 5 months old. Obviously I don't want to open the bottle but if I did and were to clean it, would this just keep happening? Why is this happening!? It does run hot... I'm running it on a 30 watt currently but I need to get a 25 watt. Is it the hea…