Surprised you did the sand before placing the rocks
I've always done it this way before my latest tank and had I not had a custom long overhanging "gravity defying" structure I would have done sand then rock and push them down as well.I like to do this as sand fills uneven crevices. I have done all 3 of my tanks this way. you just need to make sure rock is pressed down making contact with bottom glass so you don’t have an avalanche when you least expect it.
I've also pushed PVC after putting down sand to give the rocks support as well.






