Wow, these look fun, but I can decide between 2 P-series or 3 S-series. I wonder if the rebels being driven at 1000 ma restricts which leds you can replace. Bridgelux looks like they should be pushed only at 700?! Since most of the replacement colors are bridgelux they would be over driven in the rebel slots and most likely damage the diode. An S series with XM'ls and rebels might be plenty for a tank thats only 20 inches high. Hopefully we'll get more info about coverage soon so we can all start making decisions. Those picture from aquarama have me thinking you might need 1 unit per
12-18"s for good even coverage.