I did this writeup on our local board. A little copy and paste from there:
A quick writeup with my experience of SPS corals over the last three and a half years:
SPS are finicky - at least for me they are.
"Nothing good happens fast in a reef tank" - this saying pretty much sums up my philosophy.
SPS= Stability Promotes Success - the other part of my philosophy.
Swinging parameters, high nutrients, poor lighting, lack of flow: All of these factor into the success of a tank that is trying to grow SPS. They can stunt growth, cause STN/RTN (slow tissue necrosis/rapid tissue necrosis), brown polyps, or just flat out kill them.
Parameter checks:
Salinity - I check my salinity monthly with a refractometer. If you don't own a refractometer, do yourself a service and get one. $40 in this hobby is cheap, and salinity is critical to the success of any reef aquarium. Don't rely on the swing arms - they simply have too many variables and are typically pretty inaccurate.
pH - I run a calcium reactor, and probably have low pH. However, I don't measure it in my actual tank, just my reactor. This is my preference. If anything starts going wrong, and I've exhausted all other possibilities, then I may look into pH.
Calcium - 420 all day long. You can run it higher, but from what I've read, it doesn't do that much more for calcification of hard corals. Any lower than 380, and I've seen the negative effects start to occur - lack of growth namely.
Alkalinity - I run m Alk around 9.0-9.5 dKh. This is one parameter that has quite a bit of play in it. I've seen people running 15 dKh, and people that run ULNS (ultra low nutrient systems), like Neo, typically run their Alk closer to natural seawater, or around 7 dKh. Any lower than 7, and I've experienced zero growth and STN. I have also raised my Alk too high, too fast. I did this about 15 months ago in my 75. I nearly crashed the tank, cemented the sand bed, and caused STN in my SPS for several months. I lost quite a few really nice pieces, but overall, I managed to pull out of it with pretty good luck. I have a few coral that are still recovering from the Alk spike. I test Alk weekly, or daily if/when I make adjustments to my reactor
Magnesium - I run my Mg right around 1300. I test Mg bi-monthly, as I run NeoMag in my calcium reactor.
Nitrates - I prefer under 10ppm for nitrates. Any time I go over that number, I seem to experience browning out of coral and slowed growth. I maintain nitrates with water changes, feeding only pellet, nori (for tangs and foxface), occasionally mysis, and an oversized protein skimmer.
Phosphates - I don't have a good test for phosphates (not a fan of test kits for phosphates, they just don't do a good enough job). Under .03 is great for SPS. I have the Hanna handheld meter, and feel like it does a good "ballpark" job of measuring. I mostly go by the amount of algae and overall color of coral to "feel out my phosphates".
Trace elements - I don't dose anything - unless I get some phyto donated :) Other than the calcium reactor, I don't manually add any chemicals to my tank. I've tried them, and haven't had great success with them, so I've reverted back to skimmer and water changes only.
Other factors
Lighting - Another factor that has a lot of variance in it. I've ran MH almost my entire SW experience, from 175s to 150s to 250s, to T5, and eventually I'll be LED. All have their drawbacks, and all have their advantages. 175s probably have the lower advantage, IMO, as they are single end only. When I was running them 7 years ago, all they really had were spider reflectors. They've since came out with some really great SE reflectors, some that rival the best double end reflectors. 150s are great for shallower tanks, and have a great advantage of lower heat. 250s are great for faster growth, but the tradeoff is more heat output into the tank. I've experienced about a 4 degree increase in temperature since I've upgraded tanks. T5s work equally as well as 250s in my experience. The growth is the same, but the colors are much better! I'm building out my LED light in the next few weeks, so I'll be able to see how that goes as well. Lighting wasn't the only factor, but it does play a big part.
Flow - This topic has many variables as well. Throughout this hobby, there are several things that people do differently. You just need to find what works best for you, and you are comfortable with. For flow, I run a closed loop (3600gph), two powerheads (2100gph & 800gph), as well as my return of about 900gph, along with an MP40 Total that up for about 10000gph through my 120. I've been contemplating adding another vortech or two, but the cost on those seems to be my limiting factor. Other than the price, I don't see a downside to the vortechs.
Skimmer - Get the biggest skimmer you can afford! This is an integral piece of equipment to success for SPS. A skimmer that is too small for an SPS system will cause nitrates and phosphates to spike. This can cause SPS to recede tissue or RTN/STN. They can also brown out or just completely die. Skimmers are very important. Don't skimp!
Bioload - I prefer to run a very light bioload for SPS tanks. This helps reduce the amount of nutrients going into my system, which means I don't have to pull as many nutrients out. I keep two clowns, a yellow and blue tang, a foxface, and a wrasse. I'd probably be okay adding a couple more fish, but they would be small and add very little to the bioload. I will eventually trade the blue tang in for another once he outgrows the tank.
Quarantine - I am living with AEFW, so I can't say enough about this. You MUST QT every coral. I plan to run numerous frags through my QT once it is set up and then into the frag tank they will go. Once I have backups of everything, I'll dose the main tank with Levamisole. Not QTing is playing russian roulette. I dipped everything before it went into my tank, and that clearly didn't work. So set up a QT and learn to use it!
Overall, I'm very pleased with my transition to a nearly all SPS tank. There have been several struggles, but they have been great building blocks over the last couple years. I look forward to the future advancement of technology and equipment to help make SPS tanks more "user friendly".
