You can use pvc pipes with pumps on each end to act as the intake and return if you don't want to drill holes on the main tank. The problem with two pumps is that they pretty much have to be in near-perfect synchronization so no overflowing happens. Also, worse comes to worst is that what if one of the pumps fail? That's about (guesstimating) 20 gallons of water on your carpet..
No you can't do that, you will never, ever, ever get them synchronized. I'm willing to bet you cant find one example of some one who has succesfully done that. they would have to be perfectly sunchronized and the second one leaf got stuck agains the pickup it would alter the flow rate and flooding would happen. this isnt even worth attempting. Sorry Pinoy, I would have to assume you have never actually tried this and just thought it was a neat idea.
OP there are HOB overflow boxes, that work just fine if you dont want to drill your tank. I have used them for years in reef tanks, some are better than others. most are a nuiscance to start, unless you add an aqualifter pump to the top of the siphon tube. the aqualift pump also prevents siphon loss if your flow rate is low enough to allow bubble trapping. ofb's are now designed so you dont lose siphon in the case of poweroutages. in any case its super easy to modify and ofb to a non-siphon loss setup. I did this with a couple of mine that were older than dirt. I dont even think you can buy an ofb anymore that doest hold siphon in no flow.
for a sump you would need:
Sump container (be it fishtank or rubbermaid tub anythign that holds water and fits where you want to put it will work), some are 4easier to set up as a filtration and others are just cheap containers for extra water volume. there are a milluion different sump designs, the best way to start out if you plan on building your own sump is to look at what other people have done and figure out what types of filtration you want in your sump.
either- HOB OFB box - or drilled holes bulkheads plumbing.
A return pump, if your using HOB style you need to make sure the pump doesnt exceed the capacity of the HOB box at the head height.
a section of tubing or pvc plumbing (or similar) to run the water from your pump to your DT
"[Wabi-sabi] nurtures all that is authentic by acknowledging three simple realities: nothing lasts, nothing is finished, and nothing is perfect." -original author unknown-
125g marine reef tank, 6 gallon fluval edge minimalist aquascape (in progress), 1 gallon aqueon evo 2 betta tank.