(#1) I'm pretty sure tunze makes some... If you talk you to your LFS, they can probably help you find one, either a premade unit, or point you to someone who custom makes sumps. BUT...
Your best bet is to make a sump yourself... it's not that hard, and you'll be saving yourself a great a deal of money- always a good thing.
You'll be needing:
1. Standard glass tank, I don't know what size your tank is so I'll just throw the number of 100 liters out into the wind, which is a good size for the majority of tanks.
2. PVC plumbing, elbows, etc. flexible tubing will make stuff simpler.
3. Return pump: this needs to be able to pump a minimum of 100 GPH (more flow always better) taking into account the head pressure from the sump to your display. To calculate the head pressure, use this link:
http://www.reefcentral.com/calc/hlc2.php
Your probably going to need to (and want to) wait until you design your sump, but know that a few extra inches of pipe here or there in most cases isn't going to drastically change the flow rate.
4. (this answers #3) Hang on tank overflow: This is to get the water out of your tank, and into the plumbing leading to your sump.
This is the one I would use:
http://www.lifereef.com/siphon.html
Other overflow boxes will work, of course, just that one sounds like it would be the most reliable. If you want, I can get you a link to a DIY one made out of PVC pipe, which aren't as reliable... I know how to modify the design to help considerably with that though... (DIY is cheaper)
Next you would need to design your sump... Some things you need to take into account:
In order for any skimmer to achieve optimum efficiency, it needs to be placed in a compartment of the sump that is being fed with the raw water being skimmed from the surface of the display (the water- air surface is what attracts organics). In addition the section the skimmer is placed in must have as small a surface area as possible, since you want the organics to be attracted to the water-air surface in the skimmer (where it will be removed), not the sump's water surface (where it will not be removed).
So, for #4, yes you can, and you SHOULD put your skimmer in your sump.
Usually, a Refugium is built into the sump, this is an area to place a deep sand bed, grow various macro algaes and to let pods grow without getting eaten by the fish (all of this is good). A sump design utilizing a benthic area (creatures like sponges, feather dusters etc.) is an interesting concept, and definitely worth considering (link:
http://www.reefvideos.com/ (It's the one right of "carls 150g reef).
It's a good idea to leave space for an extra 20-40 liters (depending on tank size) of water, for the draining pipes, etc. when there is a power failure.
For some examples of various sump designs, explanation of the concept, etc. browse this link:
http://www.melevsreef.com/links.html (scroll down to "Sump\Refugiums & Acrylic Work").
Now, how do you build this sump?
Well...
The baffles are easy... EPDM, and plexiglass:
http://www.wetwebmedia.com/ca/volume_3/cav3i1/Baffles/baffles.htm
Then, for the plumbing...
It's mostly straght forward... have piping run from the overflow box to the drain (and skimmer) section of the sump, and from the return pump to the display.
Some tips:
- Try and minimize the amount of elbows you have, to let the water flow easier. Flex tubing is helpful, since you can spread a 90* elbow out over a few feet. Choose larger tbing over smaller tubing, larger tubing = less resistance = more water flow.
This isn't as much of an issue on the drain side as it is on the return side, as the return is where the resistance will create the biggest effect - on the drain side you just alter the max amount of water that can flow through the sump, not the actual amount.
- If microbubbles are a problem, and the source is the drain into the sump, here's what you do:
1. Add a 90* elbow to the end of the drain tubing, so the the pipe runs parrallel to the water surface.
2. Use appropriate fittings to change to a larger pipe size, this slows the water down so the bubbles start heading upwards.
3. Put a T on the end of this pipe, placed vertically. Add in pipe on the top and on the bottom. What happens is the air heads upward, while the water heads downward into your sump. Alter the length of the downward tube depending on how bad the problem is, until you find a length that takes care of the problem, if you can't find a length that will fit in your sump and take care of your problem, then you'll need to go to an even larger pipe after the 90* elbow.
- If noise from the overflow box is a problem, add in a durso standpipe(s): http://www.dursostandpipes.com/
Or an aquasilincer(s) (this was reffered to in the overflow box link I gve you): http://www.stockmanreef.com/aquasilencer.htm
How about designing?
Well... pen, ruler and paper will work... or microsoft paint (or similar, more advanced programs such as corel draw)... Personally, I like to use goole sketchup (download here:
http://sketchup.google.com/) It's quite a bit more complicated, but you get every single detail done - wich I like. For a quick how to, read this:
http://www.advancedaquarist.com/2007/3/aafeature2/view?searchterm=google sketchup
If you decide to use this program, go to "get models", then search for "piping tutorial" - you can guess why.
If you by any chance have a problem designing, give me a PM and I'll help you out.
As for your canister... if you have adequete live rock and a good skimmer, coupled with powerheads, there's no need for it.
