[Question] Why This? DIY Sump
 

Most (if not all) sump designs seem to follow this pattern

http://img13.imageshack.us/img13/745/0601090908.jpg

I would like to know why the water from the left side has to travel to the right through the bottom. What if one extends the siphon tube to the bottom of the tank, so that water naturally travels up and then flow to the right side? Is it because of air pressure? I just want to glue one less acrylic piece (lazy :oops:)

i.e.

http://img20.imageshack.us/img20/2450/sumpq.jpg

Any advice would be appreciated thanks!

im going to assume this is a freshwater sump.

google sump bubble trap.

thats not even a full bubble trap either so id suggest adding 2 extra pieces to your second drawing. both pieces on either side of that right wall, where each of the arrows are.
bubble traps are in place so the return pump doesnt suck bubbles back up to the display.

Is it necessary to worry about bubbles in a freshwater sump? I thought that was a saltwater thing?

your right, most of the bubbles come from the skimmer on a saltwater tank.. ive never had a freshwater sump but i could imagine an eyesore from bubbles in either a freshwater or saltwater display so i personally would try to avoid them.
the second picture should work just fine then unless you'll have alot of water moving through your sump (depending your drain and return pump )

One of the baffles should be high so you are directing water through your filter material, as that second drawing stands now the water in the middle will just be stagnate, if I get a chance I will take a picture of my sump.

Nevermind I already had it posted up, I have 3 baffles in mine to direct water flow
http://www.tropicalfishkeeping.com/a...d-img_2580.jpg

I really would like to build a sump for a 75. Should I use a 30 gallon for sump? I dont have a predrilled tank what type of overflow would be best in the event of power outages. I have read alot of horror stories.

Thanks.

Yea a 30 gallon should be about right with an over flow since you will need a bit extra room for the extra water drain volume, can't say to much about over flows since my sump tanks are acrylic with holes for the in and out. The one in the picture is a 20 L and that covers my 50 gallon and 30 gallon tanks and when its running its at about 13-15 gallons in the sump and that leaves enough room for the water to finish draining from the tanks and all the tubing.