The water does have a noticeable tone to it - but I can't say it's pink! Whereas the cup is bright arctic white, the water has a faint vanilla tint. Probably just because tomorrow is water change day - haha.
It seems strange that color so vivid would show up absorbed into a nylon stocking, but not be visible in the tank. Mind you, 40 gallons is different than a plastic cup. I wonder if it does effect the fish somehow? These Columbian Tetra fry developed much, much slower than the ones that I left in the tank they hatched in. They are about 3 months behind, size-wise. I chalked that up to the difference in available food and tank size. The flake-only that I fed the 40B fry when young vs. a whole 125 tank's worth of who-knows-what's in there. Also the difference in having 6' to swim in vs. 40". Jeez, every time I think about them I start panicking about getting their bigger tanks set up!
And how about Nature vs. Nurture? The fry in the 125 readily eat bloodworms and peas, spinach and other veggies - they've seen all the adult tetras in the tank do so and learned from them. The fry in the 40B, raised by themselves, only would eat flake until a few weeks ago. Now they eat peas, but won't touch other veggies or bloodworms - they ignore them like they don't recognize them as food yet. I thought that was interesting...