for your sump question, you CANNOT have just pumps pumping from sump and back. There is no way you will get equal water flow, and even if you do achieve equal water flow for a short time, changes in water flow of the pumps over time, will cause a huge flood.
You need to use an overflow box, or the drill method. Please check out my videos, I have many explaining how sumps work and how to setup sumps/refugiums.
www.youtube.com/earthling1984
