Cyano or Just Coralline

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kfig7

Aquarium Advice Apprentice
Joined
Jan 18, 2010
Messages
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I'm really confused about this growth I'm having on my live rock. I keep thinking its just coralline algae but I have never seen it grow so fast. It also is starting to get on the larger pieces of substrate I have. The rock is BRS fiji dry rock.

Never had Cyano before and I just don't really believe its that. But hey you never know. It doesn't come off the rocks easily and its not slimy whatsoever.

90 gallon tank is about 2.5 months old. Parameters are as follows:

PH - 8.4
Alk - 9.5
Calcium - 450
Ammonia - 0
Nitrite - 0
Nitrate - below 5
Phosphate - not sure didn't test

Really dont think I have excess nutrients in the tank as I cant even get my Chaeto to grow in my fuge. I also have pretty good flow. Is this just fast growing coralline or should I be worried?
 

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What spots are you talking about? The brown/green stuff or the white stuff on the rocks? Looks like its going through the algae cycling phase. You will have an outbreak of diatoms and then green algae. Eventually the coralline will out compete and take over.
 
looks like coralline to me, nice and purple.

especially if its hard to get off of rocks, lookin good!
 
coralline won't compete with diatoms. they utilize completely different food sources. what happens is the diatoms bloom, then "bust", which means they suddenly crash when the ideal circumstances change. around this time you'll see coralline algae (if any was introduced to the system) start to take hold and spread providing calcium and alk are at optimum levels.
it would give the appearance that it took over, but it's not the case.

this pink on the rock, can you blow it off with a power head? does it wipe off with your finger? if so, it's cyano.
 
It definitely doesnt blow off with a powerhead or turkey baster. I pretty much have to scrape it with my nail to get it off. It does however come off a lot easier then coraline. If its cyano I guess I need to figure out whats causing it. Definitely grows way too fast to be coralline.

I have plenty of flow (seems to be growing in high flow areas), I don't over feed, I do weelky water changes and I have chaeto in my refuge (which is not growing). I really dont do anything for phosphates so maybe I will pick something up today for that.

I guess I'm getting close to having to replace my t5 bulbs as well. Can this be causing it?
 
Do you have a phosphate test or have you had a test done showing high phosphate levels?

No reason to add GFO or a sponge for a problem that doesn't exist.

Light bulbs at end of life have a spectrum change that could cause algea outbreaks. It doesn't sound like cyano if it doesn't blow off or come off in sheets. But I'm not sure what it is.
 
i don't think there is just 1 or 2 variations of coralline algae. i think there are many. it might be coralline, since it's hard to the touch. hard to the touch says "calcium based" to me.
 
Coraline is almost impossible to scratch off with just a fingernail. I need a razorblade to get it off the glass on my tank.
 
which coralline are you speaking of? i've had plating coralline that was not too hard to remove. i've also had branching coralline that was super hard to remove.
 
Looks like coralline to me. Maybe it is growing better as your bulbs become old, as you mentioned and are putting out less intensity. IME coralline doesn't grow well under intense light.
 
I actually tried to use a toothbrush today to scrape off some of it and siphon it out. To be honest, not much if any came off the rocks so I'm definitely not convinced its cyano. Very odd.

Thanks for the input everyone. :D
 
Its fiji dry rock from BRS. Just as an update, looks like it was a combination of cyano and coralline. I added phosban to the system and in under 48 hrs., all the cyano cleared up.
 
Cyano will feel slimy to the touch, and it will have little tendrils that eventually form. It looks like this when it's really bad:

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This is the worst I have ever had cyano and it was only on one side of my tank. I purchased a powerhead specifically to point down to this area to add more flow right onto the cyano. That didn't do anything in terms of making it go away. Controlling nutrients and removing the cyano manually are most important, IMO. I got that all cleaned up and my sandbed is looking pretty good. I have never had it on the rocks.
img_1182220_0_b40d597f2abdc7816b9a7b8fe7a5b086.jpg
 
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