I'm setting up a 55 gal, and rather than buy gravel from the pet shop at such high prices, I went to just get a bag of pea gravel. Well I was looking for something dark colored and I ran across this crushed trap rock. Do you guys see any problem with using it? It is definatly smaller and more angular than what you can buy at the pet shop so I'm not completely confiadent in it. Any opinions are appricated.