Disappearing coraline algae

[lola302]

Hey everyone! I need some help identifying what could be eating the coralline algae in our 150 gallon tank, the only inverts that we have put in the tank would be blue leg hermits, and some short spiked urchins, our live rock was completely covered and in a weeks time the rock has huge white spots. Is it possible that the urchin is eating the coralline? All water parameters were checked and the calcium is at 520 but everything else is good to go, we do weekly water changes of 15 gallons, we mix our own water, with Instant Ocean and ro water.

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[Cheekymonkey]

urchins can eat corraline

 

[Reefynewby]

a few questions...

Did you just buy LR with coraline or have you had it grow on your own?

Did you mean 420 for calc? because 520 is a very high level of calcium for your tank, 420 is ideal.

And yes, urchins will eat coraline, along with a variety of other marine animals. However... to some extent coraline eating (such as what your urchin is doing) will only help the coraline spread and grow faster. This is just IME, but there is prbly some other factor causing your coraline to disappear. Coraline predators generally won't eliminate coraline from a tank.

 

[CKreef]

Have you seen any tiny starfish? Astrina stars can eat a ton of coraline

 

[JEFFTHEREEFER]

the spine urchine in the photo is your culprit

 

[lola302]

the LR came from an established tank when we purchased it 6 months ago, and it was covered completely till i noticed it recieding. i dont add any buffers to the water, i just change it 1nce a week. im gunna test it again, i use API, and i put 15 dropps and the solution is a fushia , but no blue. if it is that high, how would i go about lowering it? there are three spine urchins in the tank that guy is about he size of my palm, and the other 2 are no bigger than a 1/4 of his side. yes i have removed about 5 of those little starfish. should i remove the bigger of all the urchins of should i take them all out?

 

[Gordonious]

The urchins will do it for sure. If you find cut paths on all sides of the rock and not just gradual bleeching on the top and bottom then you can be sure it is them. Do you feed nory in your tank? If the Urchins have another source of algae they won't dig as much or as deep into the rock.

Reefynewby has a good point about them spreading the coraline. If you have only one or two rocks that you have added that are purple it would be a good idea to scrape off a bit of the coraline from them and let the bits float around the tank. These urchins can do the same thing. You may consider moving two of them to a sump or refugium, if you have one, or trading them with another hobbyist. If I were you I'd keep just one in the 150.

 

[racrumrine]

Urchins are great; but, I would second just having one. Trade the other 2 for something else.

The coralline will grow back. You can tell it's the urchin in the photo that's eating the coralline. Personally, I think it makes the tank look more natural. Watch your tank at night with a red flashlight, you'll see the urchins eating.

Asterina's will lighten up the coralline after they pass over it and the color returns quickly. An urchin will grind away the coralline down to bare rock (as yours has done).

Best of luck,

Roy

 

[Gordonious]

I had two very simular urchins in a 20 long FOWLR once. I have very little algae and my lighting was very primative. I swear they got so hungry in my tank that they started eating bare rock just hoping they would get nutrients out of it. They bored deep into the rock. You shouldn't have this in a well established reef though because you probably already have more algae then you want.

 

[racrumrine]

These look like the black urchins from the caribbean.

If they are, during the day, they live in holes in the rocks that they make, at night they crawl out and eat.

Best of luck,

Roy

 

[lola302]

thanks for all the info everyone, i think ill take the smallest out next time i see him and put him in the fuge. i think ive found the big urchine a new home, that will leave a small urchine about the size of a golf ball in the tank. i did test the calcium today and it is low, its at 340. so im gunna work on that now, i knew urchines ate algae but i never put it together that coralline is algae!

 

[lola302]

thanks for all the info everyone, i think ill take the smallest out next time i see him and put him in the fuge. i think ive found the big urchine a new home, that will leave a small urchine about the size of a golf ball in the tank. i did test the calcium today and it is low, its at 340. so im gunna work on that now, i knew urchines ate algae but i never put it together that coralline is algae!

 

[95accord]

phosphates may be a bit high which inhibits calcification for coraline to thrive.......ive been having the same problem....

 

[Atarax]

deffinitely the urchin, had one myself and would watch him do it. didnt bother me but when it got so big it knocked over rocks and corals he had to go back to the LFS.