Why do I get good growth on some SPS and not others?

Some of my SPS seem to be taking off (well to me at least Im new at this) while others barely move, am I doing something wrong here

 

No, it is your spectrum from your bulbs... Totally depends on each and every single type of coral as they all require very slightly different wavelengths for photosynthesis!
What corals aren't growing fast?

 

Just random SPS don't know the names of all but like an Orange Millepora and Orange Monti arent and then my Pocilliopora and Efflo are taking off so who knows. Im changing bulbs next month you think that should help?

 

if you get good bulbs then yes... but halides or t5?

milleporas are just really picky IMO and they only grow when they are happy :/

its odd that your monti isnt growing... most of them grow like weeds

 

Well the Monti grows just not as fast as I would like I guess, a have a pink formosa that grows fast and a purple that is losing color and not growing at all, and they are 6" (lateral) apart so go figure. As far as bulbs go Im planning on replacing my MH first prob mid Sept. I currently have the Mogul base Hamilton 250w 14k bulbs that came with the retrofit, I plan on replacing these with Mogul base Phoenix 250w 14k. Then around Nov I plan on replacing my two T5 bulbs (4' 54w) which are stock that came with the Nova with an Aquablue+ and a Fiji Pink. What do you think about that setup or do you have a better suggestion?

 

hahaha! that is actually probably exactly what i would suggest... you will get good results with that combo

after lighting the second most important factor in growth is stability. are you running a Ca reactor or dosing or anything?

if all of that is in check then the corals could just be stubborn. sometimes they take a while to get happy. my friend had a tricolor acro that took over 2 years to decide that it finally wanted to grow lol

 

Yeah I manually dose my levels stay fairly stable I shoot for 11dKh and around 450 on the Ca, as well as 1350 for Mg, good to know that some coral is just stubborn I have noticed sig growth on others so I will just have to wait and see a couple months after the new lights are in thanks alot

 

Some species grow faster than others and the same with colors even within species.

 

Some do better in higher light/flow than others. Without knowing exactly what you have though it will be impossible to tell, there's no guarantees since things vary greatly from tank to tank as well. Also like was said before some just grow slower or faster naturally. If they all still look good I wouldn't worry. Sometimes certain corals take longer to adjust to a new system as well and can take months to really take off.

 

+1 on everything above

in addition , stability is important, much like a tree, a coral will want a very secure base before growing taller and wider

if you are buying frags on frag plugs - you should notice that the plug becomes encrusted with the coral at a faster rate than the coral grows upwards and outwards

IME - having purchased many frags on plugs or rock rubble, my best growers in terms of overall mass are the ones with the most coral covering the base

Steve