Stop giving bad advice.
Because I know it will anger you with the personality traits your displaying let's dive deeper into your comments. Then you can have the last word and 'win'
OP don't let this thread discourage you. Continue with your patient attitude and continue to ask for advice and guidance as needed in the future.
How do you know that it was an error? Did you actually read what he wrote? That he changed all the sand when he moved into a larger tank? You assumed. And we know what happens when you assume.
The same could be reversed, how do you know it was correct? I'm not the only one here making assumptions. The OP stated prior that he was relaying on an LFS to test water. He stated he had it checked at 2 shops and both said he was good. Now that's another topic entirely, but I would think 2 for 2 is a good start.
You can ignore the sand, transferring the rock cycled the tank, regardless of any biofiltration capacity of either. No livestock loss, including sensitive invertebrates like his shrimp, which would lead to the conclusion ammonia never reached toxic levels.
Now I can admit my assumption with test error, it's well documented that ammonia kits are responsible for large sums of false positives. The same is true with all home hobby grade test kits, but it's more accepted by everyone on the rest.
You were in such a hurry to give your “expert” advice, that you didn’t even read what the OP wrote. What’s really comedic to me is that you said the thing that stuck out to you the most was the 0 nitrate reading, because we all know how terrible that is.
For new hobbyists 0 nitrate is usually a bigger issue than having 5-20ppm nitrate.
You didn’t even mention the .5 ammonia reading and now you’re trying to tell us that that’s no big deal.
As previously pointed out the actual 'toxic' portion of 0.5ppm reading would be so insignificant if it were correct. Whether it is or isn't, really isn't the question at the moment. The tank is cycled, but still maturing. That on top of the fact that even if it were a true 0.5ppm it would not be toxic to the coral at that level.
Even though none of the guy’s corals are opening now. I’m sure it’s due to 0 nitrate reading that his corals aren’t opening. BTW. I always have 0 nitrate readings and my corals open just fine. You can see them in my avatar.
I myself run my frag system at near 0 (according to Hanna HR). The difference is a heavy feeding and heavy filtration, along with multiple spot feeds throughout the week.
The OP has several maturity things happening with his tank. Time will fix that. The best thing for him right now is patience. Not a bunch of water changes that are going to disturb what's already working itself out.