Hi Florian & crew,
Indian Canyons is open Fri, sat & Sun, starting in July, thru, (I believe Sept), 8-5, (closed during the week.
http://indian-canyons.com/hours.html
They generally allow select tour operators to conduct tours during the week, on in certain areas.
It really is a magical place, although water will become scare until the summer showers.
Andreas Cyn generally has water, and a few refreshing pools, as you know, but many of the pools got filled in from last summers torrential rains.
There's good shade in many spots, and $5 is a lot cheaper than $23 (& soon to be parking fee) the tram charges! (It was really nice yesterday at the peak & upper Tam I have to say.
ss