Thanks for the link. I looked all over and never could find it. It's about the same size unit I ordered.
The tank is a $20 utility sink from HD made of HDPE. It's approx. 21" square, 12" deep, 20 gallon. You have the plumbing right. The 2 pipes running out of the fluid on top are used to feed the pipes on opposite sides and suspend the setup in the middle of the tank. I think Little giant has a CRC (chemical resistance chart) on the site that you can download in PDF. It rates how common materials used are effected in different chemicals. If you can't find it, I can email you a copy I got from them. PVC handles the acid with no problem
Little Giant pumps - look at the magnetic drive pumps, they have 3 grades of pumps for corrosives (MC, CS and HC) I use the 3-MD-HC on mine. A little over-kill with the HC for a 5% acid but I felt better safe than sorry. Best thing is agitation without the mist from aeration. It also cools the parts better with the extra flow.
http://www.lgpc.com/
Any questions on my setup, feel free to ask. I'm waiting on the parts to upgrade to a 60 gal setup.
SS