I just setup my 300g cichlid tank with PFS. I have an american sales warehouse by me so it was no problem getting, I check other places that normally have it but was told it was put away for the winter. I got AquaQuartz standard #20 grade. The stuff is very clean I didnt even wash it, who wants a cloudy pool right? I've even added more after tank was full with very minimal cloudiness. From what I've read it is very inert and wont affect hardness you may even want to mix in crushed coral to increase hardness. I have a 2 3/4 " layer with plants, I buried a plastic grate for the plants to attach to. Not sure what is too thick and why though.