Help with receding Pectinia colony

[Mark Hyman]

Hi all. I've had a large pectinia colony for about 10 months. For most of that time it's been happy, puffy, and growing. In the last few weeks, it's started receding and seems to have algae growing at edges and around the mouths. My water parameters are basically the same as they've been for quite a while; the only real issue I've had is trying to lower phos (currently around 0.5). That's been a lengthy battle as my rocks and sand leach more phos as I pull it out via GFO or lanth, and I've made sure not to strip out everything as I go. But again, no recent changes that I would have thought could be causing the pectinia's downturn. And my space invader pectinia seems fine, as do my SPS and softie colonies.

Any suggestions on what to do? Pull the colony and dip it? Could a pest be my issue after so long without a problem? I really don't want to lose the colony but am not sure how to help. Thanks in advance!

 

[Gumbies R Us]

Any changes to your tank?
Is this the only coral that is bothered, or are there others?

 

[Mark Hyman]

No other tank changes, and everything else seems to be doing great. Going to try dropping it lower for less light/flow and seeing if that helps.

 

[twentyleagues]

I know you said the phosphate is currently at .5. But you have been using lathium to lower it. Did you see a drop in po4? Lanthium acts fast probably faster than the po4 can rise again. Wonder if you dropped the water po4 level too fast and it effected the pectinia, but by the time you tested it was back from the rocks?

 

[Mark Hyman]

I know you said the phosphate is currently at .5. But you have been using lathium to lower it. Did you see a drop in po4? Lanthium acts fast probably faster than the po4 can rise again. Wonder if you dropped the water po4 level too fast and it effected the pectinia, but by the time you tested it was back from the rocks?

Haven’t run lanth in a few months and I always under dosed and tested to make sure phos wasn’t too low so I don’t think so. GFO hasn’t made much of a dent yet. Going to also try a couple of water changes in case there’s a trace element that’s low.

 

[Hubert J. Farnsworth]

did the PO4 creep up to 0.5 and that's when you noticed the problem? or has it been that way for a while and the pectinia looked fine up until now?

have you checked your tests for accuracy? like confirming you salinity is accurate and where you think it is? i have had a 35ppt to 38ppt salinity rise affect some corals much more than others.

if there are not really any changes that you know of i would look to your basics and something that might have changed without you realizing. is your rodi tds zero? are you using a new batch of salt, or a new batch of reagents?

i recently had two different bottles of alk reagent from the same lot test 0.9 dkh less than the previous bottle.

 

[Nor'easter Reefer]

Seems like you got some good answers above. I would agree that based on the information above it seems like it's something involved in your phos management. Or faulty test kits etc. That said, I struggle with my receding hairline, so receding corals I'll leave to more experienced reefers! That said, I wish you the best of luck, and from those pics, your tank looks beautiful!