So I got an itch to make a refugium for my 20L marine tank. My plan is to silicon a 2.5G tank to the side and let a siphon fill it while a small pump in the fuge pumps out. Has anyone had any luck with something like this? My main concern is water leaks so this is why Im leaning to glue it at the same height as the main tank.I thought about making a seaclear 70 into one but this would come out cheaper and have more volume. Any input on this is appreciated.

Thanks in advance.