how long can ill effects of alk swing last?

[gurumasta]

about 3 weeks ago i woke up to a coral starting to rtn. i checked my levels and my alk was over 14 dkh. it is normally about 11-11.4. i had tested about 3 days prior so the longest the swing could have lasted is about 2 and a half days. some of my corals lost some color and others still look unaffected. even today i came home to a coral starting to rtn. i dipped it and superglued over the dead tissue. my levels have been solid at pretty much picture perfect other than that swing for months. i am wondering if the corals that are stuggling to color back up and the ones that are starting to rtn could possibly still be from the alk swing a few weeks back.

here is my current levels

alk-11.2 dkh
ca- 420
mag- 1350
phosphate- undetectable
ammonia - undetectable
nitrite - undetectable
nitrate - 0-5 ppm

i posted this on brs as well. thanks randy.

 

[Randy Holmes-Farley]

I don't know that the RTN was due to the alkalinity itself. It's hard to say without knowing how high it went. Many folks have had alkalinity at 15 dKH without causing RTN, but perhaps other simultaneous factors came into play as well.

How did it get high?

Assuming the corals did not start to RTN, I expect the stress of high alkalinity (if any) is gone in a day after it is back to normal levels.
If it was weeks ago, and the RTN is now, I wouldn't think it due to the elevated alkalinity, although I suppose it started down a destruction pathway that you didn't really notice initially.

 

[gurumasta]

the only other change that happened in my system was i replaced my overflow boxes and forgot to aerate my fuge. im thinking it was a combo between the die off in my fuge that was down for about 24 hours, and the alk swing, but my levels spiked for a couple days from the fuge and then cycled out, so im curious as to why weeks later i still have problems. why didnt they all wipe out overnight when they were unhappy with the levels? ive lost about 3 colonies to rtn over the last couple weeks. my tank otherwise has always done well with good growth. i want to put an end to this but im not quite sure of my problem.

 

[Randy Holmes-Farley]

The RTN may have had nothing to do with the alkallinity. Exactly what causes/triggers RTN and why isn't well known, IMO. But stresses in general seem to contribute.

 

[gurumasta]

i will keep an eye out and just try to keep things as stable as possible. all levels are good now and hopefully will stay that way.


thank you very much randy.

 

[Randy Holmes-Farley]

You're welcome.

I hope you can keep it under control!