Sump Design - Request for feedback

I came up with a sump design that allows for good macro algae growth (tumbling chaeto), remote deep sand bed for nitrate reduction, and placement for the equipment that I plan to put in there.  Also, I'm not putting the skimmer in the sump because I wanted as much room in the sump as possible, and I think that it gives the whole thing a bit of a cleaner look.  Also, I was thinking about putting live rock in there, but from what I've read recently (and heard a few weeks back in our own forums), it's just as effective in trapping detritus as it is proving a home for beneficial bacteria, filter feeders and pods.  With that in mind, I decided against it.  Here's the design I'm considering at this point and I would appreciate feedback.
--AJ

 

Great feedback guys.  This is one of the reasons why I love this club; there are so many people involved that know more about this stuff than I do and are willing to share your knowledge.  Thank you!
This is my first sump build (I think my mis-placement of the ATO should be evidence of that) and I would like to get it as right as I can the first time.  To answer the questions/comments:
This is being made from an old tank - a 75 gallon tank.
About the need for an additional baffle in the chaeto area, great point.  I'll get it added.
Also good point about the skimmer return...I'll move it down to one of the other chambers...maybe make a horizontal output into the chaeto section to keep in line with the directional water flow that I'm hoping for.
I was hoping to not have to use any filter socks...because I'm lazy.    If I have to, well, I'll do it, but I would prefer not to because I know that I would forget to clean it as often as I should and the water quality would become bad due to my lack of diligence. 
As for the DSB becoming a nutrient trap, I've read that can happen if there is not enough water flow over the sandbed.  I was thinking about adding a powerhead to this chamber to prevent that from happening.  This was a great forum post on pros/cons of DSBs by Anthony Calfo here: http://forum.marinedepot.com/Topic59558-13-1.aspx
Another approach to this that I've been considering was more of a fluidized sandbed approach where I take a 10 gallon tank, install it at a higher level than the sump, and put baffles in it in such a way to force vigorous flow over the sand surface, fill it 1/2 way up with sand and allowing about 3 inches or so of water above the sand.  Instead of the baffles being attached to the sides, they would be installed to go just part of the way across the tank being attached to one side and part of the bottom.  That might give me even better results and allow me to use the area in my sump as a propagation area.  So it would look something like this when looking from the top down:
+--------------------------+
|                          === water in
|       --------------------|
|                           |
|---------------------      |
|                           |
|       --------------------|

|                           |

|---------------------      |

|                           |   
|       --------------------|

|                         === water out

+--------------------------+

I'll revise the drawings and re-upload.  Thanks again for all the feedback.
--AJ

 

Thanks Mark...I would appreciate it.  It seems like this stuff changes as much as Iowa weather.  /DesktopModules/ActiveForums/themes/_default/emoticons/wink.gif
--AJ

 

Updated design docs
--AJ

 

That little lip is the key to getting the chaeto to tumble correctly. I believe it was Steve Pro that came up with this design and has used it for years. Here's a link to a forum post where it's talked about. http://reefcentral.com/forums/showthread.php?t=462212 Great thread...great general refugium information. It's 9 pages, so a little long, but a worthwhile read.

--AJ

 

I was originally thinking the same thing, but then opted to use two separate.  The reason was that it allows me to control each one at different flow rates which should help to reduce the amount of flow tweaking to keep the GFO from tumbling too fast.  Second, if I need to turn one off for a period of time (i.e. turn off carbon for some reason), I can do that and run the other without having to reconfigure things.
The third pump in there is for an auto-water change system that I'm going to try to set up...we'll see how that goes.  The idea is to do the following daily by scheduling them in the AC3.  1) turn off return pump and let sump go to max water line  2) turn on  pump for a min or so and have it pump about 1 gallon of water out 3) turn on selenoid to allow water flow to saltwater float valve so that all of the water that's pumped out is replaced by the float valve 4) Wait to make sure that the float valve has had time to replace all water pumped out 5) turn everything back on.
I'll probably get the sump functional before I start to add the auto water change.
--AJ

 

Thanks for all the great feedback so far.  I appreciate it very much.  Any final thoughts on this?  Otherwise I'm going to order the glass to be cut so I can get started on the build.  The latest revisions can be found here for sump with equipment and here for just the sump.
--AJ