Pencil urchin hanging by tentacles

BAMslam93

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So my pencil urchin has given me the biggest headache since I got it a couple of months ago (this is month 3 and getting out of the uglies). It lost almost all its large spines to a combination of low algae/high nitrates right after cycling but now is very slowly growing them back (I posted about this issue a month ago).

Now I find it barely sticking to rocks with a few tentacles holding on and even falling and ending up on its back. Sometimes it does graze on diatoms and film algae on the glass and rocks but I get so worried about it falling that I have to move it to a new spot away from my dwarf blue leg hermit crabs. It flipped over again tonight and when I tried to help it up, a few tentacles fell off. I’m really regretting getting it and considering rehoming

Any advice or am I just worrying too much about its rock climbing behavior? I’m trying to reduce my phosphates with phosguard and will retest again in a couple of days; I hope to get some codium and gracilaria frags in the next couple of weeks to help reduce nutrients. I run a filter sock that I replace every 4 days along with a nano skimmer and 15% weekly water changes. My cleaner shrimp, snails, and hermits are doing just fine. If it helps, my calcium averages around 430-450 ppm based on my most recent Salifert test thanks to Reef Crystals. I also finished up Reef Flux to kill off bryopsis so I hope I didn’t nuke too much GHA!

IMG_6031.png IMG_6036.jpeg IMG_6037.jpeg IMG_6041.jpeg
 

ISpeakForTheSeas

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I can't tell from the pics, but what species of urchin is it? I ask because the most common pencil urchin species in the hobby, Eucidaris tribuloides, is not an herbivore - it's spongivorous in the wild and carnivorous/omnivorous in aquaria.
A lot of other "pencil urchins" in the hobby aren't actually pencil urchins (though they do have moderately thicker spines than pincushion urchins; pencil urchins have substantially thicker spines), and they eat algae, but I'm not seeing enough good algae in the FTS there for one regardless.

So, if it's not E. tribuloides, then yeah, try putting the urchin on a nori sheet and supplementing the feeding with nori or other algae for a while.
 
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BAMslam93

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I can't tell from the pics, but what species of urchin is it? I ask because the most common pencil urchin species in the hobby, Eucidaris tribuloides, is not an herbivore - it's spongivorous in the wild and carnivorous/omnivorous in aquaria.
A lot of other "pencil urchins" in the hobby aren't actually pencil urchins (though they do have moderately thicker spines than pincushion urchins; pencil urchins have substantially thicker spines), and they eat algae, but I'm not seeing enough good algae in the FTS there for one regardless.

So, if it's not E. tribuloides, then yeah, try putting the urchin on a nori sheet and supplementing the feeding with nori or other algae for a while.
When I got it, my LFS told me it was a slate pencil urchin and it had thick spines. I gave it nori sheets and it was doing pretty good for a while. There was a period when it lost so many spines, that I had to quarantine for a couple of weeks so it could recover while my tank settled down its nitrates.

About a month ago, I had a bryopsis, gha, and diatom bloom and added it back in where it was doing much better for a little bit. Absolutely avoided the diatoms on the back wall that my snails love. Should I take out the phosguard in the meantime so the other nuisance algae can grow?
 

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BAMslam93

BAMslam93

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You could always give it a piece of nori and see if fattening it up a bit helps it.
I took a break from the nori when I saw the algae take off but it’s now dying off. Just added a fresh sheet and it’s eating with the hermits
 

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ISpeakForTheSeas

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When I got it, my LFS told me it was a slate pencil urchin and it had thick spines. I gave it nori sheets and it was doing pretty good for a while. There was a period when it lost so many spines, that I had to quarantine for a couple of weeks so it could recover while my tank settled down its nitrates.

About a month ago, I had a bryopsis, gha, and diatom bloom and added it back in where it was doing much better for a little bit. Absolutely avoided the diatoms on the back wall that my snails love. Should I take out the phosguard in the meantime so the other nuisance algae can grow?
These pics are better for ID - you have a real Slate Pencil Urchin, Heterocentrotus mammilatus; it reportedly feeds primarily on coralline algae, but it eats other algae too.

I'm not sure what the best approach would be, but definitely keep supplementing it with algae to eat until you have algae for it in the tank - I don't know if you should take the phosguard out or not, but I'd make sure you change any parameters relatively slowly so it's not shocking the urchin's system with each change.
 
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BAMslam93

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These pics are better for ID - you have a real Slate Pencil Urchin, Heterocentrotus mammilatus; it reportedly feeds primarily on coralline algae, but it eats other algae too.

I'm not sure what the best approach would be, but definitely keep supplementing it with algae to eat until you have algae for it in the tank - I don't know if you should take the phosguard out or not, but I'd make sure you change any parameters relatively slowly so it's not shocking the urchin's system with each change.
Hmm, maybe it wasn't the greatest idea to do Reef Flux during the uglies since it must've killed off the gha along with that stubborn bryopsis. I did notice my urchin scraping off the fake coralline algae on the Life Rock. I moved it to the glass and added a sheet of nori; it's hasn't left and I think it's having a good breakfast with my hermit crabs lol.

I'm going to check my phosphates again tomorrow and hopefully didn't crash it with the phosguard. So far, I haven't noticed any parameters going out of whack recently (nitrates have been consistently hovering below 20 ppm, salinity stable at 35 ppm, ph stable at 8.0-8.2). I stopped testing calcium and magnesium since someone mentioned that they're not super important in a FOWLR tank but I feel like I should to make sure my tank is ready for corals and a BTA in the future.
 
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BAMslam93

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@ISpeakForTheSeas checked out my nitrate (20.3 ppm) and phosphate (0.35 ppm) after four days of phosguard. I’m considering switching to Chemi-pure Blue or Elite, reducing feeding a little (I feed my clowns TDO extra small for breakfast and a cube of frozen baby brine shrimp for dinner every day), and adding some macros to help keep nutrients low.

My urchin moved off from the nori and is now scraping the diatoms on the glass, looks like I got a bloom these past couple of days!

There’s also this weird advancing bulge of white patches consuming the algae, any idea what it is?
 

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ISpeakForTheSeas

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Sounds like its going well!

I'm personally not a fan of reducing feedings in most cases, but do what you feel you should there - the macro and Chemi-pure are good ideas; just be aware that the urchin may eat the macros if it can get to them.
There’s also this weird advancing bulge of white patches consuming the algae, any idea what it is?
It's some sort of microorganism wiping out the algae; this happens sometime and doesn't seem to be cause for any concern.
 

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