Coral growth help

[Black Phantom]

I need some advice. For some reason I just cant get a lot of my corals to grow. Ones like Candy cane and frogspawn are ok as I hand feed them but the rest just sort of hang in limbo. No growth or retraction.
Anyone got any secret formulas that they would like to share. My lights. RO water, and everything else is fine. I'm not asking for much, just a masive growth spurt that will have my tank looking like something out of a magazine

[Joe Reefer]

Could be anything. What are your Ca, ALK and Mg levels at? What corals are you talking about? Keep in mind some LPS corals take forever to grow.

[fishface]

elevated levels of phosphates will retard the growth of your corals. personally, i haven't had much luck with reagent based po4 test kits but a colorimeter had much more accurate results. i'd try to obtain a good test for po4.

[Black Phantom]

I might have to try a new phosphate kit. The tank has been running for about 5 years now so all levels are good. My water here is super hard and I go through RO filters quite fast so I wonder if that can be it.