After a period of time, you may notice a dark band forming at the top and/or bottom of some of your spectrum tubes. This is completely normal and expected, however not all of the tubes will form a band.
What you are witnessing are the impurities inside of the spectrum tube becoming oxidized. As long as the spectrum tube "lights up", then the spectrum tube is working. The only time you will need to replace a spectrum tube is when the tube no longer produces light.
The best way to verify if your spectrum tubes are producing light is to run your BioCharger in a dimly lit or dark room. If there is any sun light in the room, it can be difficult to determine if some of the tubes are producing light.
If you find that you need to replace a spectrum tube, you can order replacements from our online store.