Why Is My Bird Bath Red

This is a picture of the bird bath that used to reside at 270 Burgess Avenue.  It now resides here at the ole homestead providing refreshing water to the plethora of birds we have nesting and visiting.  You can notice where I've applied some clear chalk to prevent from leaking and further damage.

Although, I scrub it throughout the spring and summer months and winterize it by adding bleach to the water before storing for the winter, once it starts getting super hot and humid the water bird bath itself turns red, weird.

So I asked Google about this and this is the response I received.  Hmm, who knew apparently somewhat normal, so I'm not going to fret any longer - 

"The culprit for this unusual coloration is a micro-organism called Haematococcus pluvialis, which is a common inhabitant of bird batts. The red colour is due to the pigment called astaxanthin, which possibly protects the organism from the harsh sunlight, especially the ultraviolet rays from the Sun."