What leads to coralline die-off?

[jessezm]

Howdy folks, here's a question I've had over the last few weeks, and I'm hoping you all can help:

I've noticed in my 200g reef tank that the green coralline algae that has grown on the walls of the aquarium have been flaking off in large sheets over the past several weeks. I'm not sure weather or not to be concerned about this, because I've never experienced it before, but I'm curious to see what others think.

Here's a rundown of my system:
200g (240 total) SPS-dominant tank.
Lighting: 8XT5 HO overdriven with ICC660's + 2X48" VHO for actinic
Filtration: large custom recirc. meshwheel (deltec AP851 clone), 240lbs LR
Other equipment: phosban reactor (with GFO), Schuran Calcium reactor, Ozone generator (aquazone 300),OM 4-way on a Dart for circulation + Dart return pump, Fuge with chaeto on reverse light cycle

Current levels:
pH: 8.2-8.3
Temp: 77-78
Calcium: 450-480
Alk: 11.5-12 dKh
Mag: 1450
No3: undetectible (salifert)
Po4: undetectible (Hach)

Over the past two months I've made some changes to the system, including:
1) the addition of a phosban reactor and GFO
2) Nightly Pappone feedings with Amino acid supplementation (using Reef Plus by Seachem)
3) daily sugar dosing (last two weeks). While my N and P have been undetectible, I have still had an outbreak of green hair algae, which is partly why I starting dosing sugar. My sandbed is white as can be, but the algae remains on shaded areas of the rocks.
4) I recently raised my Mag over the period of a week from 1150ppm to 1450ppm, which apparently killed off a small patch of bryopsis I had.

I also now have small piles of flaked-off coralline in the corners of the tank as well....

Can anyone hazard a guess as to why the coralline would be dying, and if it is in fact something to worry about?

[jessezm]

By the way, my first guess is that the addition of the GFO might have something to do with it. But I'm confused because I feed so heavily and have a green hair algae issue as well...

[lancer99]

green coralline algae?

AFAIK, all coralline algae are red (Rhodophyta sp.)

Assuming that was a typo, elevated Mg levels can inhibit calcification by SPS....maybe with corallines as well.

-R

[m2434]

Originally posted by lancer99
green coralline algae?

AFAIK, all coralline algae are red (Rhodophyta sp.)

Assuming that was a typo, elevated Mg levels can inhibit calcification by SPS....maybe with corallines as well.

-R

Yes and no. Technically true, but in the hobby it's quite common to call any beneficial, calcifying, reef-building algae "coralline".

- Dosing sugar and raising mg are all kinda experimental procedures. Don't know of any documentation of this happening with calcifying algae as a result, but I wouldn't be surprised.

[jessezm]

My mistake--it is a green calcifying algae that has grown in sheets that are now flaking off the walls. The pink/purple coralline on the rocks is just fine.

BTW, at what concentrations does Mg begin to inhibit calcification? thanks

[acrylic_300]

I've been doing the exact same thing without the GFO. My coraline is flaking off also. My parameters are real close to yours.

Reef plus, sugar, heavy feeding, elevated magnesium.

It's one of those four.

Personally mine turned green before falling off so I figured a thin layer of algae killed it. That narrows it down to the heavy feeding, or the Reef Plus. Unless a layer of bacteria from the sugar smothered it out...or as mentioned Magnesium retarding the calcification.

You can rule out GFO IMO.

[jessezm]

Hmm.... I believe that the flaking began just a bit before I upped the mag and sugar dosing, so that seems to leave Reef Plus as a likely candidate??? Not something I would have expected...

Let me ask you a random question: do you refrigerate your reef plus? I just noticed, now that I'm halfway through the jug, that it's supposed to be refrigerated after opening...

[acrylic_300]

Yes I refrigerate everything...it probably don't matter though.

I've been dosing about 120 ml per week with 200gal water volume. I was seeing how far I could push it. Coral growth and color is good. Phosphate, Nitrate = near zero. I have a thin coat of green algae fuzz going on.

[jessezm]

Sounds just like me. I dose about that exact amount (20 ml per night) in a bit under 240 total gallons (plus the pappone at night). The green hair fuzz is mostly on rocks that are shaded a bit, and those in direct light are clean as a whistle save for a few patches here and there...

Water has been crystal clear, ORP is hovering around 430, and skimmer production has been incredible lately (must be the extra sugar dosing, cuase it wasn't doing this at all with the pappone alone). I'm emptying the skimmer cup, which is very large--10"diameter X 5" high--every two days and the stuff is dark green and nastier smelling than ever.

[acrylic_300]

I stopped the Papone and am just doing Reef Plus and heavy feeding my fish with Selcon soaked food. Thought I would mention Selcon incase that was one of your variables.

I may try using less Reef Plus...only squirting it directly on the corals with the flow shut down.

[jessezm]

I actually stopped using Selcon a few months ago when I ran out of PE mysis. Since then, I've been feeding the fish exclusively with Spectrum pellets and nori. I was actually thinking my hair algae was coming from the dry pellets, but who knows... When I get some more cash, I'll go back to mysis and selcon and see if that makes a difference.

I don't think it relates to the die-off, though...

[elkinsda]

Why are you dosing sugar in your tank? That cant possibly be good in the long run to do!

[jessezm]

Why not? I like sugar so much that I thought my fish would like it too! No, really--the theory behind sugar/vodka dosing is much better explained by others (I'm sure someone here can provide a link...), but basically the idea is to provide a carbon source for particular strains of bacteria, which then bloom, and consume nitrates and phosphates rapidly in order to limit them in your system. The bacteria is then removed via heavy filtration (i.e., skimming), and nutrients are added at the same time (amino acids, coral foods like pappone, etc.), in order to feed the corals.

I'm not sure about long-term use, or whether it's a "quick fix" for anything vs. a different way to manage a system. I'm experimenting at the moment, and generally liking the results.

I need to add a vortech or two to my system to really prevent the extra organic matter from settling out, which it has, but other than that I plan on keeping this up for another couple months at least to see if improvements in coral growth/color continue.

[acrylic_300]

Same reason here....only I believe that the bacterias are eaten by the corals and lower life forms. I only use the sugar to boost the bacteria once in a while with small doses.

It keeps the water very clear looking.

[jessezm]

Yes, that too. and I was totally blown away this week by how clear the water has been lately.