Corals Wont Open?

[HidingReefer]

Hi guys, I've got a bit of an issue with my reef. So over the last 2 days my corals haven't been opening up, however its a bit odd. My GSP, Xenia, Mushrooms, Hammer, some acans, and fox coral, these corals aren't opening up at all, which scares me as they are pretty hardy corals. However my 2 monti caps, blasts, leather, macro, and chalice are doing fine, in fact the chalice continues to grow a lot. So only around half of the corals are affected. Also around 2 days ago my skimmer failed on me. Tank info: 90 g- only 3 fish, melanurus wrasse, leopard wrasse, and yellow tang. I got my water tested, nitrates were higher than normal and pH was low. I do not understand why the xenia would not open with these conditions as they don't mind nitrates. pH was low, even though I am dose Kalk, 2 teaspoons, Alk is around 11. I also add vinegar to my ATO. I just added a fresh batch of carbon, to remove any toxins that could be a problem. I also did a 10g water change just to help out a little bit. Sorry i wrote so much, I had to mention everything that could be a factor.
Any help would be appreciated
Thanks:sad2:

 

[Dkuhlmann]

What are all of your parameters, what kind of lights and what do you have for flow? Need exact numbers on the parameters. Higher than normal and low are not parameters. We need a full set to help you.

 

[snorvich]

What are all of your parameters, what kind of lights and what do you have for flow? Need exact numbers on the parameters. Higher than normal and low are not parameters. We need a full set to help you.

This. Also what is SG?

 

[bibbe]

My finger branching coral has yellow dots any idea why n what it is? Dots like puff out