Hi everyone, I am new here and I am looking for help in building a refugium. I would like to place a 40 gallon tank below my 220 gallon tropheus tank. My goal would be to have something nice to look at that would help to remove nitrates from the tank on top. I would like to do some floating plants and there would be a tight lid on the refugium so the plants would have to like high humidity. My water is also very hard so the plants would have to like hard water. Thank you in advance for any help you can offer.