I just realized another important concept that needs to be defined, so we all are discussing the same thing: Clean vs dirty water.
The way I understand, as a general concept, cleanliness of the tank and water is always important, does not matter what you are keeping: fish, soft corals, LPS and SPS. Lack of cleanliness will lead to bacterial overgrowth, decreased oxygen content and thus lead to anaerobic bacteria bloom. That is bad and may kill your livestock.
The term clean/dirty water is often used to characterize a water with higher organics, NO3 and PO4 in reefing. Those are nutrients that all corals will use for growth and color. As most of activities reefing also go through phases, and apparently we are just coming from a Ultra Low Nutrient phase where it was believed that the less PO4 and NO3 the better to keep SPS. That is because a while ago it was very difficult to bring NO3 and PO4 down and for that reason the belief was that the lower the better and thus "zero" would be perfect. Well, that changed as most are realizing that having measurable concentrations of NO3 and PO4 is beneficial to SPS. There are even a few reports of thriving tanks with very high PO4...
The concept on the 2nd paragraph and 3rd are connected, and a high nutrient water may tip over and lead to what was described on the 2nd paragraph. Balance is the key.
With all that said I know of coral farmers that keep nutrients on the higher end and have extremely good results keeping SPS including Milleporas. Does that mean that all Milleporas like high nutrients? I would guess not. But, I would say that most SPS are able to aclimate to different situations if it is incremental and if most of the parameters (Temperature, pH, SG, Alk, Ca, NO3, PO4, Mg, light, etc...) are fairly stable.
CB
