Some Zoas Dying...Others Thriving...Confused

[madducks42]

We have a 90 gallon tank that's been up and running for almost a year now. We've taken the approach of buying small frags rather than big pieces so that we can enjoy watching them grow. Overall most of our frags have done great. Except torches. Apparently I'm a torch killer because I've tried three times and they've all died within a month. Argh. But otherwise most of our frags have done great and grown like crazy. But we've had three corals, two zoa frags and an octospawn that have died or look like they are dying in the last month. Seeing how everything else in our tank looks great I'm not really inclined to change anything but I'd love to know why these guys went downhill. Some quick specs about our tank.

- 90 gallon plus 20 gallon sump
- 2 Hydra 52's, borrowed a PAR meter from our local reefing club and the highest points of the tank get between 300-400 PAR at the height of the light cycle. Lights come on at 8am and ramp up over a 4 hour period and then start ramping down around 3pm.
- CA 420, ALK 9.2 MAG 1400, PH 8.04, Salinity 1.026

A few pictures of the ones that have died or seem to be in the process of dying. The Zoas basically melted away. The frogspawn has been mostly closed up for the last 3 weeks and hasn't grown much.








A few quick pics of some of the other corals in the tank that are doing great.












I feed the coral a few times a week, I rotate between reef chili, reef roids, and acropower. The only fish in the tank are a pair of ocellaris clownfish and a watchman goby. We used to have a emerald crab but I haven't seen him in almost a month so I'm pretty sure he died. We had him since we got the tank and he was huge so maybe he just died of old age? We have lots of blue legged hermit crabs but I've never seen them bother the coral. I'm wondering if maybe it was too much light for the two zoas that melted away? I slowly built them up to that spot over a period of 2 months and the zoas on the other side of the tank are at almost the same level of PAR and they're doing great.

 

[saltyfilmfolks]

What are the nitrates and phosphates.
Are you running gfo or other chem media?

Yea some zoas are harder to kill.
The torch thing is odd.

 

[madducks42]

We're not running gfo at the moment, we do run carbon because we had issues in the past with some of the corals not playing nice with each other. About 3-4 months ago we started having problems with dino on the sand. After doing lots of research and forum posts we thought it might have sprung up because our tank had zero nitrates and phosphates so the dino was outcompeting every other type of algae. I started dosing nitrates and phosphates about 2 months ago so since then nitrates have been around 3-5ppm and phosphates around .03. Between that and an algae scrubber in the sump our dino went away in about a month. And all of the coral started to look really good color wise and several of them started growing faster, including the three that recently took a dive.

Oh and I completely forget to mention this in my first post, but we managed to kill pulsing xenia, lol. We had a bunch of it in the tank and it all stopped "pulsing" a few months ago and then gradually withered and died. I don't remember when exactly it stopped puslsing but I know it was before I started dosing nitrates and phosphates because I was hoping it would recover with more nutrients the tank. I'm not terribly upset about it. But thought it was odd seeing how that stuff is supposed to be indestructible.

 

[saltyfilmfolks]

I’ve only killed Xenia with delay low nutints.
Yours IMO are in the sps acro range. Most zoas , like you said prefer dirtier water and so do Xenia.
IMO ime usually Xenia like extra nitrates. I didn’t test , I look at the Xenia. Lol.
Stuff like this is kinda common in a newer tank sometimes , how old is yours? Esp the dry rock ones.

Is the carbon in a bag or reactor ?
I would def reccomend some spot feeding of the zoas , sounds like you could afford the extra calories in the tank. I prefer frozen food for that actually. The juices work just fine. Rotifers work very well.

 

[madducks42]

The tank is just about a year old so still "new". And we don't have that many fish in it so even though I feed heavy there just isn't much of a bioload so I think that's why we don't have a lot of nutrients in the tank. We were on vacation last week so the nitrates dropped back down to 0 without me dosing them, but phosphates were still at least detectable when I got back. Back on the regular dosing schedule so we'll see if the frogspawn recovers. Pretty sure the orange zoa that had only one tiny polyp left is gone. I spot feed all the corals twice a week, rotating between reef chili and reef roids. I also broadcast feed acropower once a week. Aside from these three and the pulsing Xenia it seems like everyone else is happy. My best guess is that the tank had really low nutrients for a while and the pulsing Xenia just didn't recover even after I started dosing the tank. Since the rest of the tank is doing well I don't want to make any major adjustments since we're trying really hard to keep the tank as stable as possible. Hoping to add more fish in the next few months, have to go slowly because we do have ich in the tank so we're going the "ich management" route and adding fish slowly and monitoring the tank closely after new additions for any signs of ich outbreaks. My hope is that once we have more fish in the tank the nitrates and phosphates levels will become more established and I won't have to keep dosing.

 

[stevieduk]

i have two tanks, one is fish and a very large clump of xenia ( about 2 foot long by 6 inch), and the other is corals except for two young tangs. obviously the water in the coral tank is better than the fish only one. that always has high nitrates.
anyhow i recently put a small bit or zenia and some zoa frags in to my coral tank, after a month he zenia was shrinking, and the zoas, although they were out did not look very good, so I took the chance and put the zenia back in the fish only tank, along with the zoas. Within two or three days the difference was amazing, all looking much much stronger.
make of this what you will , but as Saltyfilmfolks said, they do seem to enjoy "dirtier water" with high nitrates