I think I see a couple glitches.
First, a 24V panel goes to V open when that kind of controller goes into regulation, meaning the 12V controller will see about 43V. Poof!
Next is the panels are most probably not diode protected. Those are probably by-pass diodes. Protection diodes are usually found in PVs under 20W, but you never know.
Allan down under's suggestion is good, if the 24V PV has the option for 12V.
I guess I just don't see much/any advantage to the SL controller and LCB.
A second 40W PV to series with the first for 24V, or reconfigure the 185W to 12V, and use a proper voltage SS-20 with LVD.
The way I'm thinking about it is with your diagram the 24V 185W panel is effectively reduced to a 12V 92W panel, but it will still soon be into regulation mode, reducing it to as much as 0W. And the battery is not even full yet due to surface charge. What power does go into the battery is subject to conversion (elec to chemical to elec) losses some people figure at 10%.
So the 185W panel is doing nothing...
while the 40W panel is working its butt off trying to pump water at a reduced rate, and needing a expensive LCB just to do that. If you can find a 12V pump that will operate with the requirements of power, flow, and head.
Then the sun goes down, the SL controller turns on the pump to run from an undercharged battery until the LVD shuts off the pump, leaving a dead battery, to be surface charged again the next day.
That will result in a battery being used while in a constant state of undercharge, meaning a very short life.
(cjdock nearly killed his in a month under arguably better circumstances...
http://www.fieldlines.com/story/2006/5/7/15347/13239 )
Might be a good idea to adjust or trick the LVD into shutting down the pump with the battery at a higher voltage.
I'm working on a variation of a common dump load controller now. The dump load (your pump) will come on in 3 minute (or 5 or whatever) blocks. The battery will remain fully charged. Power made will be used in 3 minute blocks. Then the load is off until the battery voltage catches up. Then on for 3 minutes again.
Ain't this fun?
G-