LPS not Expanding Fully

[JRBaker]

As the title states, none of my LPS corals are expanding fully. I have two hammers that will open, but stay much smaller than when I bought them (one has been in my tank for 6 months, the other 3 months). They did fairly well at first, but over the past month, they seem rather sad. The bubble coral, which is a fairly recent addition, is not opening at all. It was open the first week and then closed up and has stayed that way for a few days. I haven't noticed any pests bothering them. I just switched my tank from a 20 long to a 40 breeder a couple of weeks ago. No sump, aquaclear 70 HOB with filter floss (changed weekly) and carbon (changed every 4 weeks). Lighting is two Aqua Knight LED (I plan on upgrading soon). I am using an mp10 set at about 65% with a Koralia 425, placed opposite of each other. The hammers/bubble coral are placed on the far left of the tank on the sand in an area of fairly low flow and lower light.
Parameters: (Using API and Salifert test kits)
Nitrates: 0
Nitrites: 0
Ammonia: 0
pH: 8.0
Calcium: 500
Alkalinity: 12
Phosphates: 0
Salinity: 1.024
Temperature: 79 F
Maintenance: Weekly 20% water changes/replace filter floss
Fish/Inverts: Two clowns, cleaner shrimp, cerith snails, and trochus snails.
I had been using IO salt and recently switched to reef crystals. All other corals (zoas, leather, anthelia) seem to be doing well. Is my calcium/Alk too high? Nutrients too low? Any help/advice is appreciated.

 

[JRBaker]

Forgot to mention, the 20 long was had been set up for 8 months before switching to the 40 breeder. All sand/rock/equipment/water was switched over to the new tank.

 

[homer1475]

Alkalinity of 12 is a tad high, 500 CA is also a tad high. NO3 and PO4 of 0 are starving your corals. Mix the low nutrients and high alkalinity could mean your corals are rather PO'ed. Typically with a ULNS you run parameters a bit lower(Alk around 7, and cal around 400).



Nothing else jumps out at me other then you could bump the salinity up to 1.026, but that shouldn't effect the corals at all at your current level.

 

[JRBaker]

Thanks for the response. To raise nutrients, should I reduce water changes for a while? Also, do you think it would be wise to switch back to IO? While I was using IO my levels were closer to 460 calcium and 10-11 alk.

 

[Reef Bass]

Check your magnesium too. I don't see that level listed.

 

[JRBaker]

I don't have a test kit for magnesium yet, but should be getting one in a few days. I increased my feeding a little and will be switching back to instant ocean for water changes. Do you think that will be sufficient to reduce my alk/calcium?

 

[JRBaker]

I should clarify that I'm feeding a little extra to slightly raise my nitrates/phosphates, not to reduce alk/calcium. I realize I worded my previous reply a bit odd lol.

 

[Reef Bass]

Your revised statement is better.

IMHO, once achieving a cycled stabled tank, alk, ca and mag are the three big tests for stony corals. Mag is critical for proper utilization and metabolism of alk and ca. And IME, lps get grumpy when mag starts to drop below 1200.

I would let alk and ca drift down to <9 and <450.