ph is fine for the shrimp. alot of people say they need the minerals active substrate has for them to be good. i had crs on pool filter sand and they breed for me and i had babies. might be low numbers and pretty slow to breeding but it can be done.
You don't need an air stone with a sponge filter and hob. It was suggested to help you stabilize your PH for a better reading. Air exchange debases co2 from water and over time it can result in a rise in ph. But if you test half way between water changes and it doesn't change you are fine. If it changes you might want to consider a substrate with more buffering ability or raising the KH.Do you need an air stone with a sponge filter and a HOB?
Also, the substrate that I have is: Inert black gravel, Moon Sand, and Crushed Coral
What do you thing would be the best thing for substrate out of the three?
Yeah go to aqua forest aquariums website. I think its like Ada.com or something. 30$ for a 9l bag of regular amazonia.
The only thing I dislike about amazonia is that you have to cycle the substrate until it leeches no ammonia or until your filtration can get the ammnoia under control and process however much ammonia the substrate gives off in the end to 0 in less than 24 hours. Please correct me if I'm wrong guys.