The only issue I've had with gravel was when i bought red gravel. It just didn't seem to rinse well enough and the flakes where everywhere. I just scooped em all out before I put my fish in. Seems alright now. No problems with it so far.
I got some purple gravel that came with the little less than half gallon container I got at Petsmart to use as temporary housing. I never used the gravel but I don't think I want to try it if it will turn the water purple!
yep the gravel i had problems with was blue too. i checked on it last night before i went to bed, and today and i think i finally rinsed it good enough because there's nothing floating anymore. it was really random lol.
I use natural gravel and marbles, sand and stones most of the time, but I did find some awesome hot pink gravel that didn't do anything to the water Drama, what do u use for substrate if you don't use gravel?