Homebrew PCBs

I have made a etch agitator that is a mechanical resonant system. It 
is a 48 inch long, 2 inch wide and 3/4 inch thick wood board. On one 
end, it is driven by a reciprocating (up/down) scroll saw. The pivot for 
the resonant system is at 36 inches from the scroll saw. This leaves 12 
inches on the load end (etch container). The mass of the 12 inch end 
with the etch cup filled with 100 milliliters of etch solution and the 
mass of the 36 inch end becomes resonant at some RPM (Recips Per 
Minute). When I run the scroll saw at about 400 to 600 up/downs per 
minute, the assembly becomes resonant and the agitation becomes INTENSE. 
I have not ever had boards etch so fast and even before.
Using the 2 parts 3% hydrogen peroxide and 1 part of 29% hydrochloric 
acid (muratic acid), my boards etch completely in 90 seconds. I do this 
at about 75 degree outside temperature on my patio. There is some heat 
liberated in the process so the etch solution gets maybe to 90 degrees 
F. Using a rocking agitation (by hand) takes about 15 to 20 minutes to 
etch the same size board. The high etch rate seems to eliminate the 
under cutting I get with the slow 15 minute etch rate.  6/6 mil traces 
come out smooth. I have never achieved such good etching before using 
the hand agitation method.
I save the "used" etch solution in a half gallon glass jar. The jar has 
gotten full and its color was a light emerald green color. I added 
copper scraps to the jar and allowed the solution turn dark green (could 
not see through it). I strained the solution into into another jar and 
put a air stone in the solution with an small air pump, air bubbled the 
dark green solution and it turned back to an bright emerald green 
solution. Using this solution in the super agitator, after 15 minutes, 
the copper was just starting to clear.  Is this green solution supposed 
this much slower than a fresh H2O2/HCL solution.
In the super agitator, there is a LOT of liquid surface area and I pump 
fresh air through the container to keep a fresh supply of oxygen. I have 
not seen an etch rate comparison between the two types of solutions 
(fresh and green) but I did expect the green solution to etch as fast as 
the fresh solution. It isn't even close!!
I am looking for comments as to why the SLOW etch rate of the emerald 
green solution.