help with corals

so i have a 30 gallon main tank with a 10 gallon refugium check out the attachment i want to do and im also going some type of over flow.. im trying to avoid drilling but i will prob do that with 2 inch and a half flex drain pipe

I am posting some videos of my tank and what I have running on it. Please watch and tell me if you spot something that may be an issue with why corals don't seem to be prospering in the tank. Maybe the lights aren't enough or there isn't enough flow. Some corals I have are still the size they...