A question for you SPS keepers

[sfsuphysics]

What exactly is RTN/STN? I know what the acronym stands for but does anyone know what causes it? What prevents it? Why the coral can't fight it? I'm curious because I just swapped out my frag growout tank, same number of gallons but I went with a more shallow one for space. I used the same exact water (didn't do a change) and a couple of my sps frags that were tannish/brown colored have now started turning white (most of them are white) and I'm wondering why. The part that started to turn white was a piece that wasn't facing the lights so I can't see the lighting being more intense (not to mention they were high in the other tank anyways), sure I put a bit more flow in the tank, but its a diffuse flow (Seio620) and the "damaged" corals are not infront of it or anything.

Then there are some of those corals that I original got that did similar things, starting to turn white at the base and work up, but some actually stopped turning white, base is still white but the tips are all brown, and I'm fairly sure it's flesh and not diatoms because if you look from the sides its brown if you look from the tops its fluorscent greenish, and diatoms don't have that color changing ability based upon direction. Is this a STN that was halted by the corals?

I'm just curious because before I spend any serious investment in any sort of tank goodies to house SPS I'd like to get this under control and learn a tad more about what's going wrong. I mean I've heard the standard "chop off the good parts and call the rest of it a loss" responses but I want to know what causes this so I can try and prevent it.

 

[Raddogz]

Lighting, water quality, and water movement can help or hinder sps growth or death.
It's pretty much the gospel of keeping sps.

Okay, it's not the answer you were looking for.

I have one frag from Dave that has been doing that stn thing for awhile - it stn's and then it grows back. What I have found is that if I stop messing with the tank i.e. stop moving things around the sps will grow and color up on it's own.

As far as RTN goes - I've had sps fall over onto the bottom. If the sps is sitting just on the glass surface there doesn't seem to be too much of a problem - the part that touches the glass just gets a little lighter. Now if the sps falls into the detritus - that sps will rtn withing a day. (These are frags I am talking about).

 

[sfsuphysics]

Out of curiosity are frags more likely to *TN than whole colonies (all things being equal), I mean I've had frags go white and never fall in anything (maybe oils of my fingers from mounting them?). After seeing many of those Tongan reefs I'm not going to believe there's any issues with exposure to air, so I'm just trying to home in on the problem, especially if its something stupid I'm doing (ie if it happens to be me touching them). Now it could have been "moving stuff around" because I did add another pump seio620 to the tank so there's 124x turn over or as opposed to 62x (not including the HOB carbon filter).

 

[Raddogz]

In my experience "yes" frags are more likely to *tn than colonies or more established frags. I knocked so many tips off of sps that I'ved expoxied down, and it's amazing they just heal over and keep growing.

 

[Vincerama2]

I had a piece of montipora get touched by a fast encroaching "encrusting gorgonian". The parts that touched turned "dead" and that death crept up the poor monti like wildfire. I thought it wouldn't, but in a DAY, half the monti was dead (sloughing off flesh to reveal the skeleton, flesh turning white). So I fragged off unaffected branches and monted them to a rock. I took a utility knife and scored the bit that was left attached to the *tn'ing piece. THe "death" jumped the knife cut and killed the remaining bits. The fragged off pieces are doing fine.

So it seems like it's gangrene type thing, where, the death of a polyp seems to take it's neighbour down with it. If the polyps are seperated (by fragging) then it seems to not be affected...even though it's been chopped off. Maybe the dead tissue becomes toxic to the connected polyps, and it's a domino effect. Sort of like, um, if zombies invaded San Francisco, then as people are zombified, they tend to affect their neighbours, but if you chop off part of the city, the people there can survive. Or say, it's the plague or something...the only way to survive is to leave the infected colony??

Though, like Raddogz, I have a piece of (really nice brown with green polyp) monti cap, that has dead parts in it, then the live part will grow back, then some of it will die again. No idea why.

V