Thanks for all the kind comments guys, im not sure if its quartz sand but i have tried a few types of sand and gravel combos in this set up. i have found that this works for me the best i found that normal sand is just too light and gets stuck ever where when you have large fish thrashing about.
Large 5mm gravel traps waste and uneaten food where as this gravel is only 1mm but also keeps the water just on a ph of 7.0.
That's one of the best looking set ups I've seen in a long time. If I had a set up like that, I'd never leave the house. Congratts on an amazing collection.