Montipora Digitata growing but not extending

[Bootlegger]

I have German Blue (allegedly...mostly brown), common Orange, and Forest Fire. They are in my 3-month old 75 gallon tank (upgraded from my nano). They were fully extended at first but stopped extending when I changed out all of my 6x T5HO 54-watt bulbs. I changed them out over a few week period but after landing the 6th bulb, the polyps went full turtle on me. The funny thing is they are growing like crazy but hiding. They come out at night when the lights are off so I'm assuming it's the lighting.


Parameters:
Temp, 80-82
Calcium, 400-450
Magnesium: haven't tested for it yet
DKH: 8.5-9.0
Nitrates: 0
Phosphates: 0 (I know this is not entirely true as I have some bubble algae on old live rock that is still growing)

Equipment:
20 gallon sump
Aqua Euro in-sump skimmer
Knopp Calcium Reactor (the big one)
200 micro filter sock (change out every couple weeks)

Lighting:
6x T5HO 54-watt, combination of a couple actinic, blue+, and color+


Other Corals:
Starburst Monti - fully extended/growing well
Rainbow Monti - fully extended/growing well
Ora Red Planet, aka Aquarium City Red - fully extended/growing well
Oregon Tort - fully extended/growing well
Purple Stylo - fully extended/growing well
Rainbow Stylo - fully extended/growing well

Anyway, I have quite a few more corals and they all doing well for the most part. But you get my point that the plenty of other corals are doing what they are supposed to do.

Anyone else have Digitata that grows despite staying tucked in? Could it be the lighting? I don't think I have too much, 6x T5HO over a 75 gallon seems like par for the course for growing SPS.

Thanks for the help!

[Art13]

I have 4 separate pieces, one of which does what you are describing and all 4 have done at some point, not sure why. They are all purple digi. Full extension from all my other sps, grows so I don't worry about it.

[Reefvet]

Originally Posted by Bootlegger

They come out at night when the lights are off so I'm assuming it's the lighting.

If that's the only variable that's changed then you can make a reasonable assumption that it's the light. T5s can loose a lot of PAR and changing them over a week isn't a very long acclimation period.

Having said that. How can you run all this time and never measure Mg ? It's pretty important in the ionic balance of salt water.

High light, low nutrients and an imbalance in the water could easily keep many SPS from developing color.

[Bootlegger]

I'll test for Mag today. Note, I rarely test for Mag as I've never seen it swing by very much when using a calcium reactor but maybe it has. Usually my trigger to test is when my Calcium and Dkh are disproportionately out of wack.

[Bootlegger]

Solved. I swapped one of my color+ bulbs for a Blue+ and everything is now coloring up significantly better color/pop and extension is dramatically improving. As powerful as my T5s are, I'm guessing they are not getting enough PAR down to where my corals are. My tank is 24 inches tall and my lights are 6-7 inches off the water.

I am removing two of my T5s and swapping to LEDS. When I do this I'm also swapping ballasts to a higher ballast factor and lowering the lights to only 4 inches off the water. I'm guessing now with proper LEDS and properly driven T5s, my corals will get fluffy again.


Note: I had Magnesium tested and it came in at around 1300 ppm

[Icefire]

6xt5 on a 75g is plenty of light,

Polyp extension have nothing to do with less light

If they were growing you were fine

[Reefvet]

Originally Posted by Icefire

6xt5 on a 75g is plenty of light,

Polyp extension have nothing to do with less light

If they were growing you were fine

Your assumptions/opinions.

I have Digi that is so extended the polyps sway in a nice movement back and forth. They never extended fully under LEDs alone. Adding T5s and lowering them to about 350 PAR instead of the 600 they were in made all the difference.

[Bootlegger]

Yes, virtually everything I say here is an assumption based on my own perception of what I see and experience. I don't mean to sound too philosophical but this "hobby" is mostly correlative and anecdotal observations. Anyway, I've read pages and pages of opinions and assumptions on various threads of what reefers think drive polyp extension. No one really knows.

What I say above is working for my tank and may not be the answer for others. I chose to change out a bulb based on having good flows, great water quality, and zero observable parasites. I noticed my zoas were a bit dull and my forest fire monti didn't have the signature green base. To me, this means I'm not running enough blue/actinic. Thus, I added more blue. Now everything is popping the way it should and I'm getting more extension. To me, it appears (at least at the moment), the problem is solved.

Note: I used common and familiar visual indicators, more so than regular testing, to determine issues as I trust my eyes and experience. For example, I've historically found that when my Zoas are exploding with color at the bottom of my tank, I've got enough PAR (in my recent case, I found them a bit dull and - and until recently - figured they were taking a long time to adapt to the T5s). When my montis are growing fast, I assume have good DKH and calcium ratios. When my Xenia grow like weeds, I have dirty water. Conversely, when they melt away and seemingly go dormant, I've got my water quality nailed. This may not work for everyone but has worked well for me.

[Reefvet]

Originally Posted by Bootlegger

Yes, virtually everything I say here is an assumption based on my own perception of what I see and experience. I don't mean to sound too philosophical but this "hobby" is mostly correlative and anecdotal observations.

Very true. Certainly RC is 99% anecdotal.

I've worked in aquaculture research just north of you for the last 30 years. We quantify every change in very controlled, closed systems. Controls allow you make more accurate observations and thereby allow you to try to repeat and document them.

PAR, PUR and spectrum are rarely repeatable causes for polyp extension in SPS. With Zoas, nothing is constant. They're vastly different creatures and any correlation you believe between light affecting both with similar effect has never been documented in research.

Now, having said all that, there is no question light will stimulate polyp extension in some instances. The problem is it's not a consistent reaction. Some swear by MH creating PE, others T5 bulbs of certain colors.

A fellow researcher recently commented that one of my systems was showing exceptional PE because the water was 'nutrient rich.' A water analysis showed it was not. So if it's any consolation, those of use studying coral propagation for decades still speculate and are often found wrong.

[Jay_R]

Just had a look at this thread as I have 4 Monti Digit frags; A blue polyp, a forest fire, a super green and a purple. They've been in the tank a week now with no real polyp extension so far.

Params;
Calc = 450
Alk = 9.2
Mag = 1320
P04 = 0
N03 = 0.50
Temp 26c

Not sure if its just time and they're settling in.. whether it's because of the LED's (Currently have 2 x 14k, 1 x 18k and 1 x 20K Aquabeam along with 2 No Blue T5's) or the fact I have a flame angel.

Any ideas generally how long these corals sulk for when placed in a new environment?

[Jay_R]

Anyone have any experience on sulking corals?

[o2manyfish]

I get the opportunity to see a lot of people's tanks. I have some friends whose corals are all hairy and fuzzy. And then others with the same corals, and same lights without a fuzzy response.

My own tank after keeping SPS for 15+ years has never been a fuzzy coral tank. With about 100 different pcs of Acro, I have bought frags of every type of shaggy coral there is, and in my tank they usually aren't shaggy. But I get great color and good growth rates. Of the 100+ Acros in my tank there are only maybe 5-8 that have nice fuzzy polyp extension.

Dave B

[dillct]

Bump your nutrients up some and I think you'll see them take off. I've always found it helpful to run the water a little on the dirty side when acclimating to increased light levels...keeps things from bleaching.