help with acroporas

[michaelg]

I posted the following on RC, but would like some input from the peanut gallery here as well.

 

I am having some real issues with the acropora in my tank.

Basics

tank is a 58 gallon, with a lot of flow (tunze 900gph powerhead and T4 on a seaswirl).  Buld XM 20K, 400W + 2x55W PC actinics

Temp- 78-81

ph 8.4

alk 14 (yes high, turned off co2 for reactor to allow to come down)

mg 950ppm (added some last night to raise)

s.g. 1.025 using bioassay salt ***

water changes minimally 5 gallons/week

Nitrate ?  Kit on loan

Ca ?  tested, but seems kit is old.  Suspect low based on high alk

Top-Off, RO/DI ***

Carbon changed every 2 weeks.

AquaC EV-90 skimmer.

Tank run together with common sump with anenome/lps tank.

Tanks fed regularily, with home brew food and live rotifers.

 

Tips have been dying on 2 colonies of a. millepora.  These were doing fine and growing for quite some time (obtained as frags 2 years ago).  2 other acroporas seem to be dying at the tips as well.  1 staghorn type acropora has been slowly dying0 basal up tissue ressession, but real slow.  2 well established colonies RTN'd.  New additions have not faired well, including 2 montiporas. 1 well established montipora is showing patchy areas of tissue loss- doesn't look like it is being eaten though.

Note- in general, it seems something is real out of whack in the tank, but I can't figure out what.  Corraline algae growth is slow, as is the growth of the corals.  Some new frags did encrust in pretty quickly though (2 weeks) so there is some degree of growth.  Some additional info that may or may not be relavent.  Macro-Algae (grape calerpa) was cleared finally- used phosban for about a month, and had a couple of urchins in there.  Aptasia (even Eric's devil spawn variety) have been cleared by a copper banded butterfly.  I have observed the fish for quite some time, and have never seen him show any interest in the corals- every zoanthids and palyotha.  On the RO/DI, I recently changed out the filters, after all the problems happened.  I noticed that there was a rubber gasket that shouldn't have been there in the DI chamber- thus likely blocking water from passing through effectively.  The salt mix was changed from Instant Ocean starting last February.  I did it real slow, and did not notice any direct issues with it.  

As I said, I am at a loss- and am trying to figure out what has caused these problems.  I am changing 15 gallons of water tonight with oceanic salt.  I have no good reason to continue using the bio-assay salt, no improvements ever noticed, though the above problems don't seem in line with problems others have had with the salt.  I have an ozonizer that I am considering running through the skimmer.  Carbon has been changed and I will continue to change weekly.  I noticed my capnella that many of you now have has been getting whomped by the rose anenome.  Anyone want the mother colony?  I suspect it needs to be pulled and I don't have room for it anywhere else.  Any other suggestions?  The fact that corraline algae isn't growing well has me real concerned and indicates something is chemically out of whack.

 

Thanks for any help.

Michael

[iceman]

Michael,

 

When did you change bulbs or start using the phosphate remover?  

 

What you describe sounds like (1) the fluctuation in alk and CA could cause the stress;(2) low phosphates could start the bleaching as has been seen by many that use phosphate removers; (3) the bioassy salt could also have contributed...did you do a water change just before this started?  

 

Stability is the key for acros.  When I tried to switch to bioassay salt, I had similar problems with tops bleaching followed by whole colonies going from the bottom up.  With changes in alk (either high or low), I seen monti caps start to bleach...have you noticed anything there?  As for phosphates, a change in either more or less in a short time can cause acros to have problems from my experience.

 

By the way, how old is your phosphate remover?  Could it be used up and allowing phosphates back into the water?

[scott711]

Michael,

About a year and a half ago I switched from Instant Ocean to the bioassy salt. I didn't see any problems with the coral I had until I reached about the 3 month. Things didn't really look that great, new acro's would RTN and existing ones were started to have bleach marks on them and were receding. I had many small acros and monti's in my tank. I switched salt again (back to IO) and things started looking better.  I remember a post on RC about that salt, some people had great luck and others did not. Just my 2 cents.

[chideloh]

Michael,

 

I have couple of observations from my own tank.

 

1. Check for acro/monti eating nudis. Acro eating nudis are transparent and are not easily observed. You may want to remove the acros and dip it in the Lugol Iodine solution and see if any nudies are present. The monti eating nudies as you know are white and more readily observed but they are small and like to hide so you again have to take them out and inspect them and even dip them in the Lugol solution.

 

2. Maybe you have direct current toward those acros that are dying at the tips.

 

3. Alk/Cal level is again very critical, especially the level of Alk at 14. May cause RTN or STN.

 

4. I have read about low mg level may cause RTN or STN but I don't know if there is any concrete evidence of that. I have never dosed mg personally.

 

I don't think the change of salt have anything to do with it, although you never know and can't say for sure, but I doubt it.

[michaelg]

Thanks for all the suggestions.  

 

Yeah- from all that's coming back on this, I need to get the alk down.  I will test it again tonight after adding some mg, and leaving the co2 off the reactor for 2 days.

The corals aren't really bleaching.  When I have seen this before from heat, the whole coral would become pale in color.  

The bulb is about 2 months old.  This replaced an early version CV10k bulb that I had some real issues of burning corals with.

I stopped using the phosphate remover about 5 weeks ago- and only had it running for about 6 weeks total.  I haven't noticed any increase in algae, and have started feeding more again.  Usually algae is my indicator of overfeeding.

I don't think current is an issue- I have a lot of it in the tank, but it is coming from a seaswirl, a squid, and a tunze pump (that cycles between lowest and 3/4 full setting) that is deflected off the front glass.  All are pretty large bore pipes on the pieces.  The corals are spread through out the tanks as well.  

 

The nudi's may be a problem- I will really have to look for them.  Are they easiest to find at night?

3 other animals that recently had problems/died

a squamosous clam- had for 6 months

an echinopora (from the winter meeting in Feb)- never showed much if any growth, but just recently had a lot of tissue recession.

a mycedium (this one was from the summer symposia- had problems with all but one of those corals)

[iceman]

Michael,

 

You should be sure to get the Mg level up to 1200-1400 before working on the alk.  Its amazing what happens to alk and Ca whe Mg is low.

 

Something else to check on...at night check for small brown starfish at the base of your acros.  Not all are predatory on sps, but if you look at GARF's site and type in starfish on their search engine they have pictures of them.  Only reason I suggest checking this is I've found them eating some of my sps a few months ago.  I have literally removed over 200 individuals from the tank and have not had a problem with them since I starting removing them when seeing them.

 

Finally, did you notice a red bug outbreak?  I found that the red bug populations come and go, but when they are present in large numbers during the population explosion, acros tended to loose some color.

[michaelg]

No red bugs at all.  Will check out those starfish- I think I know which ones you are talking about, the goofy asymetrical ones that are kind of crunchy?   I'll get the magnesium straightened out first.  I have 15 gallons of saltwater ready to go, but might as well get the mg levels up to par first.

[iceman]

Those are the starfish I'm talking about.  The majority of them are fine, but there are a few that make a feast of acros, especially at the base and a little at a time.