Reef roids will deliver po4 to your tank. If you want to up no3, try to feed more frozen foods.Yeah I’ve been feeding more, I spot fed some reef roids also yesterday, I haven’t had them socks in for over a week, but I was changing them 3-4 days
I agree the socks are the culprit. You could always put them back in and know your helping no3. Or, just as a test, put them back in and see if they do climb back up. It will take a week or so to build back up.

