Purple tip stick

[Taylor]

Why might this purple tip digi slowly have it's tissue receding up the skeleton. I'm talking over months. I've posted some pics. My phone does not do well with leds so I hope they are useful. When I first installed it it had no encrusting and a little area of skeleton showing. Over the last couple months the tissue has receded up about a 1/4 to 3/8 inch. The tips have grown as well.
Alk pretty stable at 7.5
5-15 ppb phos.
2-5 nitrate
600 calcium, 1400 mag
Use fritz reef pro salt

Green birdsnest doing great, all acans growing heads, acro is still alive, no polyp extension however.


Is this something that is common or is it a bad deal? I only have 3 months experience with corals and I don't feel things I have read about stn rtn help.

Thanks

First image, just added April 14
Second image may 18
Last three images I tried to get close up of but it didn't help much. June 15

 

[Taylor]

Photos

 

[Richard_Cheung]

Is it shading itself in those areas that are receding?

 

[Taylor]

Possibly, I thought about it but it's a small diameter stick still, low shading. They are leds so it's not as broad of light. I'd like to hear other people comment on that.

 

[jda]

It looks like shading-based STN to me. This is why lots and lots of LED folks add T5s.

Digis are quite resilient to this... acros would be suffering more, IMO. This will get worse as it grows.

This has nothing to do with this, but in the next few months I would get that calcium down into the 450 range. Your corals will like you more if it is in balance with alk.

 

[Taylor]

I havnt figured out how to get it down. I was hoping switching from Kent Marine to rpm salt and buying more coral would let it come down. I don't dose other than kalk, that's for pH. I'll look into t5s, I have a no canopy look I like a lot so that's why I ditched t5. Plus I can't afford a fancy one.

 

[jda]

Instant Ocean is 380-400 in alk.

 

[Taylor]

Anyone +1 on stn due to led shadowing? I can't think of anything other considering health of other sps/lps. Perhaps a pest or fish? I don't see pests but I couldn't be sure it wasn't a fish.


I am making plans to use my retro fit t5 fixture with my led when I get some time and see what comes of it. If it's great results I'll build a floating canopy to hide the ugly things.

 

[DesertReefT4r]

Kalk has calcium in it. Stop dosing kalk to increase ph. Kal, is for dosing alk and cal and ph increase is a bouns result. Do some water changes along with not dosing kalk and you will be able to get your cal back to normal levels.