That's a good question, and I'm not sure. The Reefi is a very powerful light, so you would have to run it at a lower percent to not overpower the a500x potentially, but that is definitely something you can play with. It might look great. I would probably do a Reefi in the middle and a500x on each side in that situation. It really depends on your goals. Either setup is going to grow corals so it comes down to how you want it to look and what you want to spend. For me, the shimmer is
all important which is why I chose Kessil. If shimmer is super important to you, I would just stick with two a500x and consider a third if you feel it needs to be brighter. It's a really personal choice, and it all comes down to how you want it to look. The shimmer is important to me because I used to dive, and I love the way a reef looks in midday sun. It's shimmery and bright and beautiful and it makes me happy. The kessil shimmer is the closest I can get to that with an LED light, so it is worth the money to me for the way it looks. It's not just about growing corals, the tank is like therapy for me. The shimmer is everything. If I had to use t5 I wouldn't even be in the hobby. If you are looking for that Kessil shimmer but want some fill light, you can also check out
https://www.reefbrite.com/. They have a bunch of solutions for supplementing. That route will be pricier, so it just depends on how much the shimmer is worth to you. The cheapest route is two or three Reefi, but you won't get the shimmer of a Kessil.
So what is most important to you? Both the a500x and the Reefi uno pro 2 are going to grow pretty much anything so it all comes down to what you care about most. The one thing I will say for sure is I would not buy Xr30's because the reefi makes them totally pointless.
