Botton Polyps dying

[nycman]

i started my tank two years ago with easy stuff - polyps - button, star, zoas and xenia. These grew like madness and had to remove many square feet of them. Then as tank matured, I introduced LPS, mushrooms, and SPS. These are all thriving and the top third of my tank are varying types of fast growing SPS, middle part is LPS, and bottom are the polyps and xenia. While the Xenia and GSP are spreading (too much IMO), the button polps (palys) are all retreating and dying. While I am generally happy with this, as they are invasive, I am curious as to what this means. I run a ULNS, with Alk 8.5 or below, 420 calcium, temp 78, salinity 34. Any thoughts on why I am losing what should be the easiest coral in this tank?

 

[LIreefguy]

I would say the low nutrients,combined with high lighting


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[Uncle99]

i started my tank two years ago with easy stuff - polyps - button, star, zoas and xenia. These grew like madness and had to remove many square feet of them. Then as tank matured, I introduced LPS, mushrooms, and SPS. These are all thriving and the top third of my tank are varying types of fast growing SPS, middle part is LPS, and bottom are the polyps and xenia. While the Xenia and GSP are spreading (too much IMO), the button polps (palys) are all retreating and dying. While I am generally happy with this, as they are invasive, I am curious as to what this means. I run a ULNS, with Alk 8.5 or below, 420 calcium, temp 78, salinity 34. Any thoughts on why I am losing what should be the easiest coral in this tank?

ULN systems are tough on corals which need nutrients to survive.
I assume this means your nitrate and phosphate are in the undectedable range.
Needed for SPS, bad for all else.

 

[nycman]

Thanks. The thing is they thrived in the early days of the tank when lighting and nutrients were low as well.

 

[Uncle99]

It takes quite some time for lack of nutrients to make there effect.
Your tank is certainly mature now and nutrients may be quite low.
Those Xenia are nutrient sponges and may be outcompeting others.
I have actually seen people who use Xenia for N and P control, just like cheato, but instead of harvesting to the garbage, these go to the LFS...

 

[LIreefguy]

I have a remote refugium and I swear Xenia works better than Marco algae at controlling nutrients

I'll trade a rock covered in Xenia to lfs for new piece of dried rock


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