I run my fuge light 24/7- and it's doing crazy well. I highly recommend waitin until you have some nitrates for the Chaeto to feed on or you risk it dying.
I use behind the tank hang-on refuge due to lack of space. Main reasons: 1. Increase volume (my tank is 65lb so every extra gallon helps), 2. Chaeto and mangroves are growing there for water filtration. 3.Breeding pods for dragonet who wouldn't take any other food.
Question on refugium can it be too big I have a 90g tank with a 30g sump that has my protein skimmer in it. Was thinking of adding a 56g refugium next to the display tank would appreciate input on what to have in it current plan was for a deep sand bed with macro alge and pods not sure on what algee yet. should I have any snails or crabs in it? thanks for advice
Make sure you do your research on Deep sand beds or in your remote deep sand bed. I wont try to sway you one way or the other, but you should know what you're getting into.
IMO, I don’t think that your refugium can be too big, but you will probably have a hard time growing macro algae unless you stock your tank really heavy. I'm a huge fan of natural nutrient export over more pumps and more chemical removal.