Boosting the Purple!

I'm in the progress of germinating Mendo Purp seeds and I'd like feed back on how to make as much purple color as possible.
Its growing by hydroponics. As I understand it plants become more purple when its colder and when they have natural light (Via Blue/violet spectrum). Since its indoors I can only control the temperacture and I was thinking of simply putting some ice cubes in my resevoir tank to make the plants cold.
I don;t know when to start adding ice, im assuming flowering stage?

Plants don't like cold water. I have a feeling that would be hard on the roots, and depending on the size of your grow you may need a lot of ice.

If anything I would try to drop the air temp, probably in the last 4 weeks of flowering. Although color isn't really important to me, cause it wouldn't change the potency.

don't think you want to add ice to you res but you could make it to ware the temp drops at night to bring on the purple more. but cold temps and cold roots will slow growth and i think i have herd that it will hinder the final yield. the best thing to do is if it is a purple strain in the first place is to just let things run there course .you will be happy with the outcome .

this is some purple i just finished out . i did nothing to it in order to make it purple but let it run its course .

Thats some sick bud! I wont even touch the temp for my first batch then but i think i play with the temp on a later harvest.

What do you guys think are the best purple strains? i only heard of
Mendo purp
Purple haze
purple skunk
purple star.
and some kush.

Got some new ideas for boosting.
How about turning my water reservoir's temp up during night phase, and have the window open or colder air.
Also During flowering I have a hps light 400 watts and two flourescent lights. I'm thinking about putting purple tinted plexiglass in the hood of the flourescent to get that more light from the violet side of the sectrum.

What you guys think?