Welcome!
Could you get a closer pic of the refugium/sump area so we can see what the interior looks like?
Also, there's a really good chance that the cheato won't survive. Looks like you're cycling your tank, which means no PO4 or nitrates. The light alone probably won't be enough to keep it alive.
Personally, I wouldn't add cheato until the tank is established and you can use it to help control PO4/Nitrates.