20 gallon aio

I just set up my 20g Landen AIO. I bought the live rock yesterday with corraline all over it, set up my tank and added it yesterday but when I woke up today it looks like a large portion of the corraline on top that isn’t covered by sand is dying off already. The guy at the aquarium shop said...

Hey there! I’m new the the hobby. I started cycling the tank about a little over a week ago. On day 4 i notice the tank water went from clear to a red/rusty colored tint. It’s still pretty clear but in not sure what went wrong here. Since then I’ve only added rodi water to top off for any...