So if you're preparing your tank for keeping a lot more SPS, particularly acropora sp., there's a few things you might want to consider with respect to maintaining your water chemisty:
1) Acropora, as I'm sure you've read, can be quite challenging, and they are really sensitive to changes in water parameters, particularly alkalinity.
2) You'll definitely want to make absolutely sure that your measurement of specific gravity is accurate and repeatable, since the first step to keeping alkalinity and other chemistry parameters stable is the specific gravity. It's particularly important if you're using a manual "look through it" type of refractometer to be aware of the strong affect of temperature on the refractive index; you'll want to be sure to keep the drop of seawater to be measured in the refractometer for 30 seconds before reading. It's also important to calibrate a refractometer like that with an actual standard that's close to seawater - just zeroing it with RODI isn't enough.
3) Once you have your specific gravity measurements nailed, you'll want to mix up a batch of the salt you're using to 1.026 and test the alkalinity. You'll also want to test the alkalinity of your tank daily for a while so you can get a handle on how fast the alkalinity falls after a water change. For right now, it doesn't sound like much of a drop, but it wasn't clear how often you're testing. The purpose for testing your salt mix and your tank is to be sure that there's not a really large, instantaneous change in the tank's alkalinity because of a water change. That, actually, is another reason why a lot of us with SPS-heavy tanks dose; it ensures that the tank chemistry stays stable, and allows using new seawater for a water change that very closely matches the alkalinity in the tank.
4) Flow is important to acroporids, and not just the amount. Generally, you want at least 2 wavemakers in the tank that are either switched if they're the on/off AC variety, or alternately pulsed if they're the DC controllable kind. The purpose for the switching of the flow is to avoid "flow shadowing", where one side of the coral gets consistent flow, and the other side gets virtually nothing. Doing this need not be too expensive; while controllable DC pumps are nice because of their very wide adjustability and near dead silence, regular AC wavemakers like the Hydors can be switched to accomplish the same thing; they're just noisier because of the full-off to full-on nature of their operation.
5) Lighting is critically important. When VHO/Halides and then T5HO dominated the choices for SPS tanks, it was relatively rare for someone to "nuke" their acropora; most instances was someone that hadn't kept up with bulb changes for a year or more, then changed out all of their bulbs at once, which light-shocked their acropora and caused rapid tissue necrosis (RTN). In the new LED-dominated lighting era, someone nuking their corals is a lot more common. Unless someone purchased a really low-end LED fixture, the problem isn't enough light, it's way too much. Most of the commonly purchased brands like Ecotech's Radion, Aqua Illumination's Hydra, Orphek's Atlantik, and the chinese "black box" lighting fixtures like Reefbreeders have more then enough power to vaporize acropora, especially directly under the fixture. And while it's impossible to tell what the PAR is under an adjustable LED fixture without an actual PAR meter, something to keep in mind is that acropora is far more tolerant of low light levels than light that is too bright. It might take weeks to see that the coral's not growing well if the lighting is too dim, whereas light that is too bright can cause the death of the coral in one day (or less).
While you didn't specifically ask for the above, I'm interpreting that you'd like to keep SPS in general and acropora specifically in the future, and hoping those tips will be useful to you. None of the above points are "not applicable" to other stony corals, but LPS and montiporas are far, far less sensitive, so you have a lot more leeway. With respect to feeding with Reef Roids, Two Little Fishes Zooplan, and the like, there's two schools of thought. One is that the corals actively feed on the plankton substitutes and that provides them with a substantial boost of energy. The other is that feeding such foods largely simple boosts dissolved inorganic nutrients in the form of nitrate and phosphate, which the corals then absorb. If you're in this second school of thought, then it makes sense to dose inorganic nutrients in the form of sodium nitrate and/or sodium phosphate. A similar debate could be had about direct amino acid supplementation, with products such as Red Sea Energy A/B and TLF's Acropower.
You asked about faster growth; with LPS especially, folks like to keep a "dirtier" tank to promote growth, but even us SPS keepers try to stay away from a ULNS (ultra low nutrient system) by keeping nitrate at 5ppm - 10ppm, and phosphate above 50 ppb (some of us, including myself, target 200 ppb). A ULNS can be successful, but those tanks typically employ really heavy feeding to make up for little or no dissolved inorganic nutrients in the water.
