Losing chalice, leptastrea, favia etc

[GOSKN5]

For the last few months I have had an issue with chalice, leptastrea, favia etc...

My tank is mixed reef and has tons of montipora, shrooms, zoas, birdsnest, softies, euphyllias, etc.. all doing fine and growing...

But in the last month I have lost 2 chalice, one one the way out.. losing a portion of a nice favia, leptastrea frag, acan enchinata... I also noticed a small spot on my space invaders pectinia.. which I have had for almost a year...

My parameters are all stable and in order
Alk- 9
Cal- 450
Mag- 1400

Using red Sea test kit and dosing 2 part daily..

Running 4 t5 bulbs with an ice cap ballast and a 150w blue LED strip.. 120 gallon tank.. all corals affected are in the lower half of tank... (pectinia about halfway up)...

Any thoughts?? Here are some bad pics of the affected corals..

FTS

 

[Diesel]

Looks to me something is stinging your corals as I see some tube worms in some of the pics and they can bother the corals as well.
You never posted your nitrate and phosphate?
Pectina can be to high if your ALK is at 9 and No3 is low, the light gets a hold on it that way.

 

[Salty1962]

How old are your bulbs?

 

[nervousmonkey]

Agree with diesel. Something is getting to your corals. That combined with one more factor, such as high all and low nutrients, will be enough to tip the scales...

 

[GOSKN5]

I have not tested nitrate and phosphate, I would guess both are fairly low as I run barebottom, feed lightly and run gfo... also doing weekly siphon and water changes...

What would be a better number for alk? Should I let it drop at once or gradually?

There are tons of tube worms, but not really near the affected corals (other than the leptastrea pic)...

 

[GOSKN5]

How old are your bulbs?

Bulbs are all less than 4 months old

 

[nervousmonkey]

your alk is fine, mine is a little above yours, but I don't care about NO3 levels in that tank, as it is mostly LPS and softies, a couple acros, but they still do well in the tank. I run an SPS tank at alk of 8 as I am controlling NO3 and PO4 levels, but you are not in a bad range of alk, except if your tank is an ULNS tank, or you have really low nutrient levels. High alk signals to corals that they can grow quickly, so they grow skeletal tissue as calcium carbonate, but cannot build the protein based cellular structures that give the color, flesh, etc. of your corals, and sometimes the tissue dies and recedes, as the corals cannot get enough food to stay at the weight they are at, much like a human that doesn't eat.

Don't drop your alk quickly, if you do decide to lower it, do it slowly. That would not be my first choice of treatment though.

Do you feed your tank often? That's what I would start with, and don't worry too much about increased levels of nutrients, watch your corals rather than the numbers. I find feeding corals solves a lot of issues...

 

[GOSKN5]

I feed frozen once a day.. there are 18 fish in the tank.. all are small with the chromis being by far the largest...

It is barebottom, running gfo, filter socks, big skimmer, and weekly water changes.. but the glass needs cleaning twice a week or so...

 

[nervousmonkey]

how about feeding your corals? That is really what I meant to say.
Sounds like you have good means of nutrient export, and I would venture to guess that you have very low nutrient levels, as you use GFO with a big skimmer and run barebottom with weekly water changes. That sounds like you have very low nutrients. What are your NO3 and PO4 levels? Do you know? If not, that's OK, but start feeding your corals some quality food, meaty foods for those corals that eat meaty foods, and I would not broadcast feed unless you have no time at all. Spot feed with a turkey baster, etc. with pumps off, so your corals can get the food they need. At least see if that helps the corals that are not doing well....