Thanks for the added info fredro!
What do you guys tend to do for SPS browning out? I had the base of my green slimer that has been doing well starting to brown in it's lower base. My wild bonsai is doing the same. Research says either lighting too low or nutrients too high.
Questions going forward instead:
Lighting: Did you do a PAR reading to decide where your corals go?
Placement: How do you know which area to place X sps or is it based on wherever you have free space to place it?
Issues like STN/RTN, Browning out, getting pale/losing color: reasons for it and what has been your fix? Do certain corals just die like some zoas are just likely melters?
What do you dose or feel is necessary to add to the tank for coral growth and coloration?
Any of these answered questions will help. I have seen many members tanks when I visit them but honestly don't have the time to go over all these questions while I'm there. Helps to give everyone in MR a place to go to get an experienced reefers opinion.
Brown SPS, as your research suggested, not enough light or too much nutrient. Also happens in stressed corals i.e. shipping, or handling a coral too much.
For Lighting and coral placement PAR is in the back of my mind, but not the deciding factor. I look at the population of zoox within the SPS. If it has deep rich color, it will handle more light. If color is faded or pastel go easy on the light. Nutrient level is just as important. Whether you're running ULN or higher nutrient, you know what your system will do to colors, keep this in mind for placement.
The reason why I absolutely hate LED lighting as a primary source is the spread. Close to the diode you will get a bright appearance and good coverage, but as the corals get further from the diode, the light illuminates the corals from a steep angle, illuminating only a small portion of coral. Signs of low light can be visible (green base, base STN), but the LED user can also burn the tips at the same time when they crank their LED settings. Burn one side, not enough light on the other, no real light penetration through dense coral growth. LED's make me want to PUKE, especially after I read all the agenda driven reviews. I highly suggest T5's for new SPS keepers due to the uniformity of light. It makes coral placement predictable, and illuminates evenly. I would suggest moving on to LED/T5 or halide/T5 when you have a better understanding of SPS keeping.
RTN- Happens for many reasons, most of the time I'm not really sure why. Most of my RTN occurs soon after I put a stress out out coral in my tank, or when a coral in my tank has a poor spot for a long time (low light, or flow).
STN- I get this from GFO use sometime, not sure why. Also notice stn from base when a coral is not getting enough light, or my alk drops too low for my nutrient level. As a rule, a low nutrient reef maintains Alk close to natural seawater 7.5-7.7 DKH, where a high nutrient will want to stay around 8.5-9.5 DKH (or more) for better growth and health.
Necessary additives- None really, but I do ike microbe-lift Special blend. It helps keep the tank biologically stable IMO. The most important thing is to have a good amount of fish and feed them often. The SPS will absorb the nutrient and have better color if everything is spot on. Of course there are other additives to "feed" coral and manipulate nutrient level, but unless you are an experienced SPS keeper I would Stay away. It's tough balancing things using additives and carbon sources, systems such as zeovit.
IMO carbon dosing in general (including pellets) should be avoided by new SPS keepers. This is a delicate balance to keep. If you mess up, your SPS are dead.
Keep a clean, fed tank, with traditional lighting, good flow, and steady parameters. Your SPS will do great. You can tweak certain aspects as you gain confidence and knowledge in SPS keeping.