2 Questions and will this idea work?

[Casino]

What it the pump which was pumping water into the sump stoped working, What would keep the retun pump from running dry?

What if the return pump stoped working, what would stop the pump thats pumping water into the sump drain the tank and flood the house?

I dont know anything about sumps. I just have a general idea but have these questions. My tank isnt driled and no overflo. I was thinking of getting another pump and using my remora HOB. I would HOB my remora off a sump, have the MJ that I have pump into the remora that is HOB of the sump, let it skim water in the sump, and have it pumped back into the tank. I was thinking, all I have for circulation is a Eheim ecco, since I need a PH to add circulation to the tank, well Ill use the return to catch 2 fish with 1 net. I dont know if it will work, but It was just an idea I came up with.

[Saltyone]

Your best bet is to get an OVERFLOW Box, that eliminates a pump pumping from your tank into your sump. Also you will NEVE matcdh the flow rate of 2 pumps if one wears a little faster than the other it will pump less. With an over flow box water from the tank is gravity fed into the Sump then only ONE pump in the sump return it to the tank. If that pump ever stops, all water flow stops. the overflow box will not feed anymore water in to the sump once it reaches the water level.

How you have it now if the return pump stops, you better get you flippers and alot of towels csause your pump will keep pumping water untill the water level drops below it. abd vice versa. Your much better off getting an OverFlow box thats the way to go using a sump. Not 2 pumps. Try this link out here it is how they work

http://atlas.csd.net/~cgadd/aqua/overflow.htm