Dino... again... I know...

[taricha]

thats why I would like to have an identification of the Dino. But the more I look to the pics the less confident I an with the identification.

Also, everything I read associate dinoflagellates with zero Phosphates and Nitrates... but my values are much the opposite... I don't get it!!!

these are a dino, amphidinium, but aren't the most typical kind. These may go into the water. It seems they are toxic. I would run UV. Red showing up in your skimmer is a strong indicator that UV will help.