Alright, that is quite a few fish but it isn't too many either.
If you find that an entire cube is not being eaten, split the cube in half. Feed 1/2 a cube a day and see how that goes. As long as your fish retain a nice thick body conformation, they are being fed enough. If you see belly dipping of the fish or its getting thinner, increase the amount of food you feed. You don't necessarily need to feed 3 times a day for your species of fish. Some species of fish, like anthias, require consistent feeding thru out the entire day but with what you have, 1 meal a day is plenty.
Controlling nitrates and phosphates requires more attention since you have a good number of fish. Reducing the amount you feed does indeed reduce the nitrates and phosphates in your tank, however, even if the fish consume all the food, they aren't necessarily retaining all of it, especially adult fish who are no longer growing. This will just end up as nitrates and phosphates. If your system is no longer removing these efficiently to levels to that you prefer, you will need to update your removal system.
So, if you reduce the amount you feed, you could indeed reduce nitrate and phosphate down to levels that you would prefer but that means you possibly could starve your fish which I'm sure your not for. lol. However, since you already have all these inhabitants, I would recommend increasing your nitrate and phosphate removal systems, this way you can continue to feed your fish properly. As your young pajamas grow, the amount of food they require will increase and so will your nitrates and phosphates. If you haven't already done so, start with some macro algae, grow it and either discard it, sell it or give it away to export the nitrates and phosphates. You can also go with biopellets to remove nitrates and phosphates but biopellets are only effective when nitrates are present. If your tank can efficiently remove nitrates or keep it relatively low, use GFO to remove the phosphates. You can load up your tank with quite a few inhabitants as long as you have the bacteria to process the ammonia -> nitrite-> nitrate and then provide systems that remove large amounts of nitrate and phosphate that you introduce in to the system when feeding all your inhabitants. Make sure you read up on these types of nitrate and phosphate removal systems because I may have given you the answer to dealing with nitrates and phosphates but these systems still need to be well understood and managed properly to work as intended. They aren't simply plug and win systems.
Now for food types, I would recommend adding some omnivorous food source, it can be pellets, flake or frozen to supplement their diets, to keep their diets balanced.
There is a scientific study of marine food out there that was done that can help you choose what type of food you want to feed to reduce the amount of phosphates. If you google it you should be able to find it, if I'm not mistaken, it was actually done by Randy Holmes who is a chemist that is very active on these forums. In his study, I recall a section in which it states that rinsing food makes very little difference. The amount of phosphate removed by rinsing the food is literally insignificant. It is a great read and will definitely benefit you.
Happy Reefing!
