slowly receding LPS... thoughts?


New member
I've noticed that a number of my chalices are starting to develop a "receding tissue" problem... they're still alive (no RTN), but while some of them are growing, others are shrinking (and you can see the skeleton underneath starting to become exposed).

My chemistry seems to be within acceptable parameters (with the exception of slightly elevated phosphate levels, which I've always had without problems for my LPS), and so I don't think that is the problem (though it might be)?

I think I'm feeding enough (oyster feast and arctipods), so that's probably not the issue either.

However, I do have a tank of mixed LPS and SPS, so I'm wondering if maybe the strain of chemical warfare is finally taking its toll on the less hardy pieces?

Any thoughts on the situation would be greatly appreciated!

Grant W

New member
Which LPS are having trouble and what are your actual test results? Any info will help. Has your salinity gone up or down dramatically lately? Do you run carbon or gfo? Temp swings with the heat we've been having......


New member
Thanks for the feedback...

As of a few minutes ago, here are my test results:

ph 8.3 *
dkh 8.4 *
salinity 21.5
calcium 410 *
mag 1200 **
phoshate .75 **
ammonia 0 ***
nitrite 0 ***
nitrate 0 ***

* salifert, pretty new test kits (exp. dates all 2013 or later)
** elos, slightly older test kits... but both purchased within last 12 months
*** API, admittedly older test kits... though even when they were new, they were registering "undetectable" levels

The only other "event" I can think of that might be tied to the start of the problem is that it began shortly after I hooked up a used chiller to the tank (in June)... it is keeping the temp stable on these hot days, but is it possible it might be leaching something into the tank?

Also, I was under the impression "1200" was an ok target for my mag levels... though perhaps I need to be shooting for that 1400 level too?

Thanks again for feedback!


New member
Oh - forgot to answer some of Grant's questions...

I have a small bag each of carbon and phosban in my sump;

salinity is pretty stable, dkh does fluctuate between 7 and 9 depending on my dosing diligence - too wide maybe?

If chiller is working (and it seems to be), temp stays between 79 and 81.

impacted corals - previously robust acros, roughly half of my chalices (though the other half have good color and are growing), part of a candycane, a couple of my acans.

not impacted - pocillopora and stylophora, branching hammer, the other half of chalices, favia (these are growing the best of anything in my tank right now), acans, blastos.

Ah - Also forgot to mention in my last post that my other thought is whether or not the sponges I asked the board about a few weeks ago might be behind the problem...

Anyhow, thanks again!


New member
LPS needs mag to be in range or they will recede. Raise it to 1350 and they will come back ;) You probably notice your sps are loosing color too right?

Elos is a good test kit for Mag, your phosphate be better if it is zero. dial back your feeding and use some GFO and carbon if you can.
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Grant W

New member
Over how long a period of time has the "slow" decline taken place? What is your water change routine? Any basic changes recently, salt, supplements,etc.


New member
Thanks for all the feedback!

First off, I added some mag via two dosings today, roughly 5 hours apart... though color improvement alone does not indicate victory, I have to say that my acans all were noticeably "brighter" by the end of the day (more contrast between shades of color, and the brighter colors were more "glowing")... we'll see what the next few weeks bring (though since I've been aiming for 1200 and folks here are saying 1400, it seems like a reasonable place to start).

No major changes in anything lately, other than attaching the chiller to the tank shortly before I noticed "issues" starting to develop... which was in mid-June or thereabouts (so the "slow" decline has taken place over a period of roughly 3 months).

Guy - my salinity is 21.5 on the side of the hydrometer scale I use, which translates to around 29 on the other side of the scale... does that number seem closer to what you'd be expecting?

Either way, here's to hoping that raising the alk levels solves the problem!

Thanks again for the input!


New member
>> Any stray voltage from the chiller pump.... <<

Good question... and I'm not sure of the answer. I bought the chiller from Mike, and I do vaguely remember him having some unexplained die-offs at some point as well maybe?

Can it be checked easily with a cheap toy from the hardware store? or how can I go about testing the idea (besides turning the chiller off for several weeks... which will be an option soon, but not quite yet - I think we've got at least one more hot spell ahead of us still)?

Given the noticeable difference just from boosting my mag levels today, I am hopeful that that is actually the problem... but totally willing to consider all possibilities!

Thanks again for your help!

PS in the post above, I meant raising the mag (not alk) levels


New member
Here is my two cents, I had a hydnophora doing the same thing. It turns out that there is such a thing as STN that takes place from months to weeks. I clipped the dead tips and then used seachems reef dip and a couple hours later it really spruced up. It's been a few days and the regrowth is amazing. I really recommend the dip, best of luck.

Reef Bass

colors and textures
I was able to get by this summer without hooking up my chiller. Yay Petaluma. Yay fans and open tank and sump tops.

Nate I went through a long period of gradual lps decline that led to the demise of many of them. I figured out once I paid about a dollar a day to kill a scoly over six months. Joy. (not!)

In my case, I believe it was accumulated detritus in the sandbed which I had not been maintaining that caused a gradual decline in water quality. When I started maintaining the sandbed (vacuum on water change, stir ever couple weeks), the recession stopped, color improved and the survivors started growing again. Cyano also went away.

As far as stray voltage goes, I've found the easiest test kit is a hand with a small cut on it. Insert into sump. No tingle, no stray voltage. Yes, this is an extremely caveman approach. I also find it interesting how no cut, no tingle.

I am also unfamiliar with your salinty units of measurement. I recognize that there is another scale which is used, but the 1.0 - 1.030 measure of specific gravity is what I'm used to. Whatever scale you're using, are you sure it's properly calibrated?
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New member
Great ideas coming in!

It seems I am frequently in possession of a voltage test kit, and I can pretty comfortably rule "stray voltage" out (no pun intended) - thanks for the tip, Ken!

I will add a more vigorous stirring of the sandbed during water changes to my list of things to do, though again, I am really hopeful that it is just the mag levels that have been kept a little too low for a long time.

Looking at my hydrometer, the scale I have always read is "specific gravity," and the line drawn right next to it with the other scale is "salinity"... so they should be equivalent readings. Not sure why I have always looked at the s.g. number (perhaps 'cuz I used to make beer and so the term was a more natural one for me to use when I got into reefing?), but that's the scoop on my salinity readings...

Thanks again!
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Grant W

New member
I would tend to lean more towards Kens thought re maintenance issues prior to messing with the water parameters too much but the mag should be in the 1350 range

Grant W

New member
If I can add another thought without being abused for it.... Did you flush the chiller before hookup, there could have been some nasty stuff just sitting in the heat exchanger and piping. Just a thought