No worries.because im a big dummy and really spit balling on this electrical stuff can you explain a little more on how these work?
For DC, its as simple as Volts * Amps. 5A @ 12V is 60W (5 * 12).
The pumps there claim 11W peak. At @12V this is (11 / 12) = 0.92 Amps. So three of them are just fine.
(I had a typo for 80W before, corrected to 60W).
You don't want to put all the loads at 100%, so buffer at about 80% - which gives 48W for a good steady state.