Do you have fish in the aquarium already? If you do, I'd reccomend buying live rock and cycling it in a trash can with a heater, a powerful powerhead or pump and put the lid on it. Do water changes on it once a week until your NH3 and NO2 are gone. Then it will be ok to add to your aquarium. Its much easier to just lay down the cash all at once because doing this is a pain the arse.
The crushed gravel is ok for reef tanks. Sand works better because it's more conducive to growing microorganisms in the sand as well as anerobic bacteria. But you don't need it.
A skimmer that's rated for 120 gallons is something I wouldn't put on anything larger than a 50 gallon honestly. On reef tanks, protein export is very important esepcially with sps corals and over filtration is key. You want as much nasty brown stuff coming out as possible. That said, I also wouldn't go bigger than double the reccomended tank size. This is because the skimmer is designed to make foam and if you don't have enough proteins in your aquarium, it won't make the appropriate amount of foam to let the skimmer work properly.
As far as water movement, you need MORE. Lots more. Unless your powerheads are pushing 500 gals an hour. On my old reef tank I only had one powerhead but I had a surge device that dumped 4 gals of water into the tank every 8 minutes. The tank was only 55 gallon. That was a lot of water movement. And everything loved it. Especially my rose anemone.
For the fluval, take out all the media. It would be useful for doing carbon once a month and phosphate remover if so desired, but it should just be used for water movement or not at all. Look into getting a sump and an overflow box. It makes life so much easier with reef tanks especially of that size.
The crushed gravel is ok for reef tanks. Sand works better because it's more conducive to growing microorganisms in the sand as well as anerobic bacteria. But you don't need it.
A skimmer that's rated for 120 gallons is something I wouldn't put on anything larger than a 50 gallon honestly. On reef tanks, protein export is very important esepcially with sps corals and over filtration is key. You want as much nasty brown stuff coming out as possible. That said, I also wouldn't go bigger than double the reccomended tank size. This is because the skimmer is designed to make foam and if you don't have enough proteins in your aquarium, it won't make the appropriate amount of foam to let the skimmer work properly.
As far as water movement, you need MORE. Lots more. Unless your powerheads are pushing 500 gals an hour. On my old reef tank I only had one powerhead but I had a surge device that dumped 4 gals of water into the tank every 8 minutes. The tank was only 55 gallon. That was a lot of water movement. And everything loved it. Especially my rose anemone.
For the fluval, take out all the media. It would be useful for doing carbon once a month and phosphate remover if so desired, but it should just be used for water movement or not at all. Look into getting a sump and an overflow box. It makes life so much easier with reef tanks especially of that size.
