Trickle filter into refugium

[Budda619]

This might be a dumb question but here goes. I have a 30 gallon tank. In the back it appears it has a built in sump where my skimmer resides. On the right side is a wet dry trickle filter. Is it possible for me to turn the wet dry filter in to a refugium? Or should i just have a separate 10 gallon as a refugium?

 

[Budda619]

One of my rain trays are empty, i dont use the bio balls. Is it possible to grow some macro algae in there? And skip a whole seperate tank for refugium?