Looking for add on sump- undrilled tanks

here is a idea! it looks inexpensive for this hobbie. watch all 4 parts they do a side by side comparison. Dave

http://www.youtube.com/watch?v=mF_QporOTvo

 

Do you mean to have both tanks up and running while sharing the same sump for filtration?

I'm actually thinking about doing that here with in the next few months. What I'm going to do is buy a bigger pump and T off the pump so it pumps to both tanks so they will have enough flow and build an over flow from my new tank and pipe it into my sump where my 72 is now going.

You just need to build your sump how you want it and pipe it to both tanks. What all would you like in your sump? Live Rock, Chaeto algae, sand, Refugium? Will your protein skimmer, pump, and other mechanical filtration be in the sump or external?

It's not that it's difficult by any means, it's just you have so many options to work with it'll feel over whelming at first, but once you build one and get it going, you'll know for next time what to do differently.

 

I am running a 55, 90 and 240 off of one 55 gallon sump. The 90 is upstairs and the rest are down. The size of pump will depend on how much flow you need out of it (considering supplemental flow in the tanks) and how far you have to pump. If you are planning on pumping upstairs like mine you will need a pressure rated pump. The Mags won't cut it for this. I really like my Dolphin 4700 pump, but this is probably more than you want. So are you pumping on the same floor of to a second level?

 

A mag 12 is about 1200GPH so if you divide that between two tanks it is about 600GPH each without any head height. If you are across the room I assume you go will up over the ceiling?? If so you will lose GPH from pushing the water up. This can be significant. At 600GPH you will need supplemental flow for SPS but I am guessing you have that. Put some sort of ball valve to each tank to control flow.
Watch out for CPR overflows. They have a bad rep of overflowing. I am actually a fan of them but you have to be diligent in their care and cleaning. Use an Aqualifter and check it daily for flow. Routinely clean the aqualifter and lines. If you don't follow these steps one day you will have a bunch of water on the floor.