Well, my first thought would be to take the gravel out and get yourself some rock or stones that don't have the shimmer. You can get river rocks of various sizes that look natural. I too, tried putting the small fish tank gravel in my first vase, (I have always had my betas in a vase, not a tank, so I don't use a filter) and I found it was harder to clean, because his poo just got caught up in the gravel and I would have to clean it all everytime I changed his water. I don't use anything now in his vase.