It will be fine for a little while, but you would be better off with a true live sand/aragonite/crushed coral/calcium carbonate to buffer your pH/alkalinity and calcium levels. Otherwise you'll end up dosing way too many supplements down the road in a futile attempt to maintain your alkalinity. Trust me on this, I just watched my coworker struggle to maintain these levels when he had regular silica beach sand. After he replaced 50% of the substrate with aragonite, he hasn't had to dose alkalinity at all. Before he was dosing over 2tbs of soda ash per day in a 75g! You can also put some crushed coral in a media reactor if you really want to keep your substrate. I use black sand in my 10g reef and Just have a bag of aragonite in my HOB filter.
I can go into way more depth about this process if you like, but the short answer if you're gonna need to buy some crushed coral.
I am a marine biologist and I have worked in the aquarium trade for 3 years. I have worked in 2 stores, maintained freshwater and reef tanks professionally, and I am a fish consultant for a store now.
