Patent ID: 7361225

Claim:
A liquid tank, comprising: a process bath; an agitation service bath assembly comprising an agitation service bath, the process bath and the agitation service bath being separated by a partition plate over which process liquid staying in said process bath flows out to said agitation service bath, the agitation service bath assembly, further comprising an agitation room arranged under a bottom portion of said agitation service bath, wherein the process liquid from the agitation service bath flows into the agitation room, said process liquid in said agitation service bath is agitated by an agitation means provided in said agitation room; a liquid supply tunnel through which said process liquid goes from said agitation room to said process bath; and a liquid supply outlet located at an end of said liquid supply tunnel and opens to said process bath at a bottom portion of said process bath, wherein the agitation room comprises an agitation rod and wherein the agitation rod is shaped like a column having a side laid on a bottom of the agitation room and configured to rotate horizontally, thereby supplying the process liquid through the liquid supply tunnel into the process bath which raises a level of a liquid surface of the process liquid in the process bath and causes the process liquid in the process bath to flow out over the partition plate to the agitation service bath.