Several Corals Struggling, Help!

My tank has been up and running for almost a year now and I've never really had any problems with coral health. Recently, I've been having issues. I had a birds next die about 3 weeks ago. It was showing good growth but we had a cold spell (-10 for several days) and I struggled to keep my tank up to temp and it fluctuated. It dipped to 75 and then I got it back up to 79. I think that was its demise.

I've had steady temps in my tank since then but now i'm having issues with a few corals.

Perimeters:

Ammonia - 0
Nitrite - 0
Nitrate - 0
Phosphate - 0
Calcium - 445
Alkalinity - 6.104
Magnesium - 1480
PH - 8.2
Salinity - 1.025
Last Water Change - 4 weeks ago

Pic #1 - Organ Pipe Coral - Has been closed up for a few days now. It did the same when it was really cold but opened back up nicely after that for two weeks. Now it's been closed back up.

Pic #2 - Torch Coral - Has been closed up for 2 days now. It did the same when it was really cold but opened back up nicely after that for two weeks. Now it's been closed back up. When fully open, I've noticed it's kinda brown except the tips.

Pic #3 - Bright Red Montipora Capricornis - This piece was doing really well and showing good signs of growth. The far right 1/8" is new. I noticed that it was starting to brown out and I thought it might be the lights so I moved it down to the bottom. It's continued to brown out.

Pic #4 - Candy Cane - I've had this coral for about 7 months now and it was doing great. One day I noticed it was shrinking in size so I moved it down thinking it was the light (it was mid tank right under a light). Since then, it's continued to get smaller and now i'm starting to see the skeleton.

Pic #5 - Can't Remember the name - This coral is about 5 months old and has been doing great. Yesterday, I noticed the white spots on the tips of a few branches. Is this growth or is it starting to head south?

I forgot to add alk a few days ago and noticed it dipped to 5.554. I bright it up to 6.5 and then 7.5. Could this be the issue?

All of my zoas, ricordeas, sympodium, pavona & acans are doing great!

Anyone have any ideas as to what is going on with these 5 corals?

Thanks!

 

I'm guessing it's the alk issue with it being so low....

 

don't think the temp would be it at 75F, and as OFK said, the Alk is a tad low.
Is it usually in the 6's?

 

Do you have a heater on the tank?

What test kits are you using?

Volume of water please?

Nice job of posting essential information in the leading post, thank you that really helps, just need a couple more stats.

 

I meant post the test kits I used... but forgot.

Ammonia - 0 - API
Nitrite - 0 - API
Nitrate - 0 - API
Phosphate - 0 API
Calcium - 445 - Red Sea
Alkalinity - 6.104 - Hana Checker
Magnesium - 1480 - Salifert
PH - 8.2 - API
Salinity - 1.025 - Refractometer

My display tank is 110G and my sump has about 15G in it. I have around 100 LBS of BRS Reef Saver Rock in the tank and a 2" sand bed.

 

Andy I would definitely bring up the ALK to 7 or 8 as suggested above. You'll want to figure how you're going to bring it up and maintain it ie: Dosing, more frequent water changes, change of salt mix.....I would use a calculator like 3reefs or BRS to figure out the dosing to reach your target value.

The temp swings and the ALK swings are most likely responsible for your stony coral issues, adjusting those should and prevent swings as able will probably alleviate the problems.

You're going to want to keep monitoring the Calcium as your bring the ALK up. You're going to want to get a handle on the Ca/Alk ratio.

http://reefkeeping.com/issues/2004-12/rhf/index.htm

 

I will read the link you gave me today.

I really need to do more frequent water changes. I seem to slack on doing those. As for salt mix, and recommendations? Currently, I've been using instant ocean.

As for keeping the Alk, Cal & Mag at stable levels. I've built another stand that will house a 10 gal ATO tank and above that, I will have 3 dosing pumps set up. I purchased this stuff around Christmas time and have been taking my time building it. I ordered the stain yesterday and as soon as I get my trim back from the guy routeing the edges I should be up and running. I'm sick of doing manual dosing and can't wait to get this automatic dosing cabinet up and running.

I'm guessing the monti is probably too far gone to recover? Also, what are your thoughts of pic #5? Is the white tips showing signs of dying?

Thanks!

 

#5 looks like a Pocillopora, hard to tell from the image but that does look new growth. As long as there is tissue on the Montipora it can recover.

Reef Crystals mixes at over 11 if I remember correctly. Red Sea Pro mixed higher as well.

 

When you say you are using Instant Ocean is it Instant Ocean/Instant Ocean or Instant Ocean/Reef Crystals?

 

Sorry, i'm using reef crystals.