SPS basically need 3 things in order to be happy: good water flow, lighting, and water quality.
Water flow: SPS do best in high flow environments. This does not mean placing them in front of a powerhead! They want broad, random flow, not a jet blast from a maxi jet. Generally, you'll be pushing upwards of 40x your tank volume per hour to make them happy. Good broad flow powerheads would be Koralia, Tunze, or Vortech. Vortech and Tunze can truly be randomized to allow optimal flow. I personally run 2x Vortech MP40s in my SPS reef.
Lighting: SPS need strong lighting in order to have best coloration and growth. I personally am a huge fan of T5 lighting and get excellent coloration with my ATI sunpower. You can provide too much light however, or too long of a photoperiod. I run my lights for 8 hours a day, with only 6 hours of intense light. If your acros are brown, then it could be because of too little light.
Water quality: This one is probably the most complex. There are so many factors that go into water quality. SPS need calcium and magnesium levels to be in line: Ca at 400-450 and mg 1250-1350 generally. Alkalinity is probably the most important. I keep mine at 8.5, but 8-10 is generally a good range. It's not just about the exact value, but about stability. SPS do not respond well to large swings in alkalinity. If you dose alkalinity in one big dose each week, you'll end up with some unhappy sps as opposed to dosing everyday in small amounts. Along with these big 3, you'll need a steady temperature as well. Another component of water quality are nitrates and phosphates. Generally the lower the better, but you can have them too low. All corals need nitrate and phosphate in very small amounts. Generally you'll want phosphate .03ppm or lower and nitrate 1ppm or lower. This can be accomplished with heavy skimming, filter socks, refugiums, carbon and gfo. Of course water changes are a major part of good water quality as well. If you notice your sps start to go pale, then you have likely driven nutrients too low.
Invest in some quality test kits, make sure your parameters are good and go from there. Don't try to change a bunch of things at once, you will cause even more problems. SPS like stability. Be patient, have good tank husbandry, and things will fall into place.