Dumb Question time,

OK, I am planning on setting up a sump this round but I don't really know how to go about it. I am also planning on getting a bigger tank and use my old one as the sump. All of my equiptment fits to my old tank so i was thinking maybe I would not have to buy all new stuff if I still kept the equiptment on the old tank.

Get a drilled tank with at least bulkheads if not internal overflows already installed. Much easier to octo-proof than a hang on external overflow. From there you can pretty much use your imagination and some pvc pieces. http://www.melevsreef.com/acrylics/sumps/glass/

How large of a tank would the sump need to be for a 30 or 40 gallon aquarium?

As large as you want to make it really. Whatever size tank will fit in the stand. Just consider what you want to do with the sump, what equipment you want to run in it and how much space you will need in it to accomplish that.

What would be a better size for a 30-40 gal
5 gal or 20gal?

At least a 20.

The bigger the better.

If you want a good skimmer, these will be big. Choose your skimmer, then decide on a sump size that can fit this and everything else you may want to keep in it. If the sump is large enough, you can also section off a refugium.

Can anybody post some pictures of their overflow or sump so that I Know what I am dealing with.

Thanks

Here are images of my older setup which is probably closer to what youll be needing.

http://thetentacleparadox.com/CuttleFarmArmy-TheFarmOld.htm

Eventually on that system, All water from the overflow went directly into the 'recirculating' skimmer then to a chamber with more live rock, and then to a chamber where the return pump was.

My current setup has all the pumps external for reduced heat in the system. This can be seen here http://thetentacleparadox.com/CuttleFarmArmy-TheFarm.htm

:sad:No new pictures. I thought you mentioned adding something for the cuttles recently - always enjoy your tank creativity.

Thanks Paradox!
I think I have got it now but feel free to post more.

Oh yeah, does anyone know where I could get my tank drilled? I asked at one of my LFSs and he said that nobody does that anymore.
Do I have to buy a pre drilled tank?

I think DHyslop and Paradox posted instructions for doing it yourself:

http://www.tonmo.com/forums/showthread.php?t=10306

I don't remember anyone having problems finding an LFS to do it before, and I'd also expect that a glass shop or a good hardware store might be able to as well.

I purchased glass hole drilling bits on ebay. They aren't the best quality, but will work for more than I need. Remember to DRILL SLOW with lots of liquid to cool the bit.

The sump needs to be large enough to hold the regular water level in the sump plus the extra water from the tank when the pump is off and the water drains down. I would suggest a 20 gallon for a 30/40 gallon tank only because anything smaller would not hold the drainoff.

Take a long time to plan your sump and get good bulkheads and it will payoff later.