What is a penis rash? There are multiple conditions that can cause a rash on the penis or in the groin. Rashes are commonly itchy and can be caused by something as simple as an irritation to certain soaps or something as complex as an infection caused by fungus, an STD or pubic lice.
Purple on the fixtures and fittings and plaster = very high chlorine stabilizer or conditioner levels. It can also be caused by metals and/or minerals in the water, particularâ¦ly manganese. The manganese reacts to the high level of chlorine (when you shock your pool for example) and turns the water purple.
The quinine in tonic water causes it to grow bright blue under a black light. Science Photo Library / Getty Images The bitter flavoring of tonic water is due to the presence of quinine, which glows blue-white when placed under a black light. You'll see the glow in both regular and diet tonic water.