Need help" poor polyp extension

[reefdude135]

I have a tank issue that I have been unable to diagnose: poor polyp extension. It is strange... my tank does well. I have close to 100% fish survival rate over many years. I just can figure this out.

Calcium and Alk are within range; Ammonia/Nitrate/Nitrites are 0/0/10. I perform weekly water changes of 10%. I dose with 2 part daily (with alk on a drip). Only additive is a FM vita of some nature. No carbon or other filtration. Use reef frenzy 1 to 2 times per week. Fish feed mostly on Spectrum pellets.

In terms of corals:

• SPS: montis (encrusting and caps) grow very well. Acros do fine too. But their polyp extension is poor. Just horrible, non-existent.
  
• LPS: Acans do terrible for me; they shrivel and compress with no feeder extension. Tracys and scolys do the same. Poor survival rate. But other LPS -- brains, micros, and candy canes -- do fine.

Hardware: Lighting is 250w hamilton MH 14k. I have a good skimmer and a Tunze and Korilia 1 in a 6 foot tank for flow.


Does anyone have any ideas? Help!

 

[Hiker_]

Your flow is way too low for a 6ft tank. I have a K1, K2, a KNano and the return line(447gph) all for flow in my 29g tank. SPS require high flow and high lighting. The acans like moderate flow and moderate lighting. They do best on the sand or very low on the rock..

 

[GOLFREEFER]

Maybe phosphate issues? Do you have any algae issues? Everything else sounds o.k., except the flow but that shouldn't cause pe problems.

 

[username in use]

What kind of fish? anything that may be nipping?

 

[reefdude135]

A few responses:

Flow: I had a pair of Tunze before, but went to just one because I thought the acans might be getting too much flow.

Algae: not an issue. minor glass dusting every few days, but that's about it.

Phosphate: I don't think so. all water goes through RO/DI.

Fish: I have some pygmy angels and a yellow goby, but they don't seem to bother anything. They are well fed.

 

[GOLFREEFER]

Ah, pigmy angels could explain it. I know people have had great success with them in SPS tanks but I would never do it unless the tank had huge quantities of colonies.

I would put money on it being the angels. Sorry it is 50/50 chance they will nip at corals.

http://www.reefcentral.com/forums/showthread.php?t=1557401

 

[rkelley_10]

As aforementioned, lack of PE is usually retraction to protect from physical insult (nipping) or from low flow. I have two mp40w's at full steam as well as and iwaki wmd40 for the return and another on a closed-loop with an oceans motions 4-way. I'm about to get another mp40w to further randomize and intensify flow.

 

[lbaldrey]

Some observations over time from my tank...

I had poor PE on my acro colonies till i got my nitrate and phosphates down close to 0.

Low Alk and the candycane wouldnt expand.

Nipping / Pests caused Zoanthids to close up.

 

[reefdude135]

Thanks!

My Candy Canes are huge and exploding! The zoanthids are doing well too.

Nitrates is like 5 ppm. I have not checked for phosphates lately though.

One suggestion made to me was to start running carbon, something that I currently do not use. I'll be starting this week,