RTN and salinity

[Clownguy]

Got a question for everyone, I am reintroducing some of my frags that I was saving over at a friends house after my tank drained and when I checked on them this morning they had RTNed over night. Could this be caused by high salinity? I checked all of my parameters and they were no3=0 no2=0 nh4=0 pH=8.4 Ca=430 and my salinity=1.030. I figured it was probably the big shift in salinity the caused the RTN so I have spent most of today slowly bringing it down and will bring it to normal levels by tomorrow. I didn't even think to check salinity before I put them in because the couple of other sps I have in there were doing fine but they had probably got use to the gradual increase in salinty. So I guess my question is do you think the high salinity is what caused the RTN or could it have be new lights? Thanks.

Chris

 

[mojoreef]

Could have been a combination of both. I am not sure what Salinity you were coming from but a coule of points isnt usually to much. SPS are like most corals with the exception that they dont tolerate parameter swings to well, temp and Ph being the to big ones. In the case of lighting this is also a big swing for corals and will cause rtn in a heartbeat. Corals have internal regulators of oxygen, since they use photosynthisis in thier growth cycle. To much light can create to much oxygen, it can even create hyper oxygen and create hydrogen peroxide (not a nice thing ) the coral uses enzymes to regulate this, but if it goes to far the enzymes will shut down the coral, exspell zoox along with a whole lot of other nasty things.
So probibly a combo of a few things, lighting, salinity, shock from moving and so on.


Mike

 

[kevinpo]

IME sudden increases in lighting intensity is a major cause of RTN in SPS corals.

You don't mention what your alkalinity is. That is another important parameter. Sudden shifts upward in alkalinity can also cause RTN.

HTH,
Kevin

 

[NaH2O]

Mike and Kevin - thanks for posting about the lighting. I have a question about light intensity and water clarity. As you know, I've lost most of my corals to RTN since my tear down and set-up. One thing that I noticed with the tank since it is set-up again, is an increase in the water clarity. A general increase in clarity (not so much detritus in the water). Could this increase in clarity, cause the lighting to put another stressor on my corals (big stress being the tear down and set-up)? I had considered putting some window screen over the tank - specifically the remaining corals, as an experiment to try and salvage what I have left. I've been wondering about the water clarity and lights, and your posts have me wondering even more.

 

[mojoreef]

Sure clarity will allow more photon energy to penetrate and thus more energy to the corals


Mike

 

[kevinpo]

Carbon and ozone can both change water clarity enough to turn corals brown or in extreme cases cause RTN due to the sudden increase in light intensity. Usually it is a combination of factors that trigger an RTN event. They don't have to occur at the same time. For example your temperature may have been running a bit high for a few weeks without any problems. Then you add carbon a week later, then you change bulbs the next week. The next day you notice a coral or two beginning to lose tissue and you connect it to the new bulbs. This is only one example. There are dozens of combinations that could occur. We tend remember and attach the most importance to the most recent events. Normally bulb changes of the same wattage but different K ratings cause color shifts in corals rather than triggering RTN events when all other parameters are near the norm.

HTH,
Kevin