Corals not opening all the way

[BSej]

Hi all, I've got a 20-gallon cube been running for 2-3 years. I've only had fish/coral for a year or so, though. Some of my LPS are only like a fifth of the way open. The torches, and frogspawn specifically. The monti and other basic sps seem to be growing great. Goniopora looks good, and the one hammer looks good.

Tank has two gladiator clowns, pincushion urchin, and CUC.

Parameters:
1.025 sg
Nitrates 2.5
Phosphates .09
Magnesium 1250
Calcium 450
Alkalinity 7.3

They were previously much more open, but over the course of several weeks have shrunk. I haven't done water changes much, but I'm not sure what that would solve. The only thing I can think of to do now is a few more water changes over the course of a few weeks. Thanks for any help in advance!

 

[dvgyfresh]

When was the last time you changed carbon?

 

[BSej]

When was the last time you changed carbon?

I don't run carbon

 

[dvgyfresh]

Water changes may be a good idea , with a mixed reef I would run carbon due to chemical warfare

 

[Mr. Mojo Rising]

It sounds like your high flow corals are doing well and its the low flow corals that are struggling so it might be a flow issue if you have sps type flow. For me, adequate flow for different type of corals is the biggest challenge I have in my own mixed reef tank

 

[BSej]

It sounds like your high flow corals are doing well and its the low flow corals that are struggling so it might be a flow issue if you have sps type flow. For me, adequate flow for different type of corals is the biggest challenge I have in my own mixed reef tank

I’m pretty sure there isn’t too much flow on those guys. I just have one power head by the sps on top, pretty low flow on the lps.