I too was almost the victim of this clown!! But his tune was busted once I asked him for his PayPal info for the payment and he ran for the hills... this is the best approach for payment, everyone is covered :)
I agree with the masses - lower your Alk first and foremost. From your pic, seems as your SPS they are on the sand. What Par are you getting at the bottom of your tank?
Two AI 16s would work easily but if you don't want to have to push them too hard, I would do three of them for a much better spread on a 48" aquarium. It will give you a piece of mind for a future proof system down the road, if you want to sneak in an SPS into the mix 😉