Unfortunately, I was recently able to witness the effects of mixing pool chemicals together. I responded to a call for help that was caused by mixing Calcium Hypoclorite (Cal Hypo) and Black Algaecide- Trichloroisocyanuric Acid(Trichlor?) together. I do not know if water was introduced to the two powders that were mixed together in a bucket. My guess is that the powders were mixed dry, and then water was added to them. The result was explosive.
The person who mixed them had chemical burns on his face, chest, eyes and inhalation injuries to his lungs. He was transported to a local emergency room and that is all I know of his condition.
This is just a reminder to be careful with your pool chemicals. Never mix with other chemicals, unless the label directs you to do so. I don't know if that is ever necessary. Anyway, read the label carefully and wear eye protection.
It is easy to become complacent when you get used to using chemicals. I always knew that the chemicals are hazardous, but it is different to actually see the results first hand. I just wanted to pass along the safety reminder. Hopefully it might save someone on the forum from experiencing their own "first hand experience".