Fwiw,
I’m putting a 24 inch Aquatic Life fixture with 2x AI Prime HD’s over an Innovative Marine 50.
You could get almost the same PAR over your 40, using the same fixture with your Hydra 26, depending on hanging height of course.
I went with the 2 AI Primes due to the larger footprint of the tank. I can spread them as needed & they have a little more power than the 26.