If you are going the fish tank route, you might check this out:
http://www.fineartphotosupply.com/printwasherpage.htm
Looks pretty reasonable for the time it will save.
I'll have to agree 100% with Fred Picker. Quote; "No running
water, no agitation! Archival washing requires time, clean
water, and print separation."
I achieve all that using a tray and hydrophobic separators.
The separator material is available from fabric outlets. It is
known as interfacing and is of non-woven polyester.
Two trays and $5 for the interfacing are all that is needed.
The second tray is used for transfer to fresh water. After an
adequate pre-wash archival processing the prints may be
held in a first tray; 8x10s, perhaps a half dozen.
I won't go into detail as the transfers to and from one tray
to a second is quite straight forward. Be sure though that a
separator is at bottom and on top of stack. Likely any that
use the method will find three soaks after the hold will do.
For those that process in the usual manor I suggest 1, 2,
and 3 hour soaks. I usually overnight my last soak. As a nod
to agitation a transfer with same water can be made once or
twice during any one soak. Simply pour the water from the
one tray to the second then peel and place the prints and
separators in the second. Water use? Extremely low. Dan