Which one should I use in my tank with crypts, swords and anubias? Does Onyx sand really affect the water pH? What is everybody's opinions on these products?
both are very similar. i use it for small and large tanks and also have not found onyx to shift the water's ph too much, if any at all. depends on taste but i think onyx contrasts better with green plants, flourite will give a warmer feel to the tank.
I chose Onyx sand over Flourite b/c I prefer a uniform colored floor. Haven't noticed pH difference (weekly water changes, CO2 injection).
Ditto Cearbhail, its a an individual thing.
Both will work.