A little browning and a little stn or dying tissue started a few weeks ago

HB AL · Sep 9, 2017

So I've noticed a little browning and a bit of stn or dying encrusting tissue on a few of my acro colonies that started a few weeks ago or so. These are small colonies that have grown from frags for the last year and a half. I haven't changed a thing in my regimen since it's been working for me and it's simple. Tank water volume is around 90 gallons or so including sump. From day 1 when I set up this tank I've done 15 gallon water changes around once every 1.5 months, right now it's been 3 months. So I'm gonna do a 20 or 25 gallon water change today. Everything in the tank is thriving and growing except for a few of the above mentioned pieces. I dose alk, calcium and magnesium along with some trace elements once a week.
My Params are as follows measured with salifert test kits.
Alk = 8.5
Calcium= 450
Mag= 1350
Nitrate and phosphate really low I only check those maybe once a month
Salinity with refractometer 1.025
Water temp 79f
The few acros I've noticed with what I consider minor changes for now have been in the same place forever and are higher up in the tank. They get lots of light from my 5 Kessil 160's the same it's been the same since day one.
So at this point I'm figuring since I lagged a little on this latest water change ( been 3 months ) versus the regular 1.5 interval maybe that is the reason for the slight change in some of those corals. I've used Red Sea pro salt since day one.
Not gonna do anything drastic at this point since it's just a few corals showing negative changes and not the whole system. So I'm assuming a water change of 20 gallons or so is a good idea for know and will see if they go back to there normal colors and growth rates in the next few weeks. If there's anything that I might have missed any info would be appreciated, as although I consider my regimen successful I'm always up for any good advice.
This is a full tank shot from yesterday and the coral with the most browning and the one with what looks like dying tissue in a section of where it encrusted.

HB AL · Sep 11, 2017

After everyone's replies with advice after 3 days of the post being up ;Bored , I went with a simple 20 gallon water change yesterday and dipped the acro with the dying encrusting zone. Thanks for the tips, I thought this was the best reef community forum to ask for others opinions and tips. Glad I have a couple of good lfs's here I can rely on when I have any questions that I'm not sure of the best recourse and where some quick advice from an expert Would be appreciated.

Denisk · Sep 29, 2017

HB AL said:
After everyone's replies with advice after 3 days of the post being up ;Bored , I went with a simple 20 gallon water change yesterday and dipped the acro with the dying encrusting zone. Thanks for the tips, I thought this was the best reef community forum to ask for others opinions and tips. Glad I have a couple of good lfs's here I can rely on when I have any questions that I'm not sure of the best recourse and where some quick advice from an expert Would be appreciated.

Sorry to hear there wasn’t much help offered. I usually see browning when phosphate/nitrate is little high with a lower alk. But that doesn’t seem to be the problem. I also noticed you run carbon in another thread and I’ve had great success running no carbon to very little. Not saying that’s the issue but maybe it was stripping the water.

Hopefully the water change will help but no matter what, you have a great looking tank!!