Acropora Tip recession?

[cabrego]

Hey guys,

Some of my SPS have been showing signs of tissue recession at the tips. The corals affect lately are:

acropora nana
Purple bonsai
other unknown aropora

Parameters are:

9 dkh
375 Ca
Mg 1350
sal 1.025

My Tank is 2 years old- and the 3 or 4 acroporas suffering range from small frags to larger colonies. I should also note I have another large tableing acro that does not seems to be suffering, blue stag not suffering, and many other corals doing fine.

The only thing I have really changed in the past month was upping my Mg dosing from 1 ml to 15 ml per day. This has raised my mg by 100 ppm over the past 3 weeks.

What can I do to try to fix this problem?

 

[Radioheadx14]

Has your dkh fluctuated recently?

 

[cabrego]

The last time I tested dkh was July 18 and the dkh was about 12-so it has droped about 3 points in 3 weeks. I don't know how fast it dropped-but I assume it was a fairly slow drop corresponding to the depletion of my Kalk reactor (my Kalk reactor is about due for a refill).

My records show that I have had drops as high as 4 points (10 to 6 in 2 weeks) and I did not note any tip recession. But now I see some from 12 to 9 so I am not sure if dkh drop is to blame...any thoughts?

 

[jfingers8]

dkh of 6 will give you problems. it doesn't mean your going to start noticing something the following day. i would blame it on not having your alk stable. i had the same problem at one point. keep it stable for a while and they should bounce back. if it starts growing algae on it cut the tips off.

 

[cabrego]

dkh of 6 will give you problems. it doesn't mean your going to start noticing something the following day. i would blame it on not having your alk stable. i had the same problem at one point. keep it stable for a while and they should bounce back. if it starts growing algae on it cut the tips off.

Right now my dkh is at 9 and 3 weeks ago it was at 12. When it was at 6 I didn't see any problems. Anyway, I will be doing a water change tomorrow and I will refill my Kalk reactor the alk is usually pretty stable, but since the kalk started running low the CA and ALK have dropped over the last 3 weeks.

thanks for the input.