Chronicology 101: Will ice water turn pot purple?
Well the short answer to this question is NO. A longer answer is that, watering your plants with ice water is more likely to shock and kill them than it is to turn them purple. But, either way, the answer is NO.
The problem with feeding your plants ice water or extremely cold water is that it will shock the roots. This is the same thing that will happen if you feed your plants extremely hot water. Additionally, feeding your plants water with to many dissolved solids will cause them to absorb less than desirable amounts of any fertilizer you may add to the water, this is more important for hydroponic grows than soil grows though.
The reason that turning down the temperatures in your grow room is effective at turning your pot purple is because it causes stress to the leaves and the buds of the plant. So, stressing the roots is a good way to stress the roots, duh, but not a good way to stress the buds. Decreasing temperatures, especially during dark hours, is a tolerable form of stress for most strains, because this is very similar to outdoor/natural growing conditions.
You need to consider that stressing your plant will have an effect on the overall quality of the finished buds. If you are growing for yourself, well then you want to have the best product possible. At least, I hope you do. And, if you are growing for someone else (i.e. a dispensary or to sell to others) well they are more likely to appreciate the fact that your pot knocks them on their ass than that it is purple. I mean, the best weed I ever smoked was green, I’ll put that out there. We called it The Truth.
Let’s see. High. Rambling. What else do I need to cover here?
The quest for purple pot reminds me of something that some shady dealers and growers will do to make there pot appear to be of a higher quality. I feel like it doesn’t happen so much anymore, but I have heard of people spraying pot with a light layer of windex. When it dries it appears as though the pot has more crystals on it. The bud will taste different, but not terribly so. If you don’t believe me, try it for yourself, but I don’t recommend it by any means.
Additionally, you could probably die the buds purple by spraying them or feeding them purple die. But, again, if you have some put you on your ass shit, no one will care what color it is. And, that’s the truth.