one of *those* questions... can too much light cause SPS bleaching?

[jacksonpt]

I've struggled with my sps keeping good color pretty much forever. I recently bought 2 undata colonies and placed them on the sand bed for 2 weeks. Both pieces were doing well so I moved one up to the middle of the tank and left the other down low. almost immediately the higher-placed coral began to lose color while the lower one still looks great.

Lower colony is a basic purple, higher colony is yellow with teal polyps.

Tank is 18" deep with a 4 bulb T5 retro kit. 2 actinics run for about 14 hours, a daylight and another actinic run for about 4 hours.

water params are far from ideal, but not terrible. no other coral is showing any signs of being unhappy.

 

[dreaminmel]

Short answer, yes too much light can cause SPS bleaching.

Long answer, there may be something else at play. You say water params are far from ideal. Do you have #'s?

 

[jacksonpt]

I agree, I'm pretty sure there's something else at least in play, if not to blame... I'm just trying to identify and then isolate whatever variables I can.

Params:
salinity: 1.026
temp: 77 or 80, depending on which thermometer you believe (glass or stick-on)
ph: between 8.0 and 8.3
po4: always reads zero, but I have algae growth, so there is some there feeding the algae
mg: always around 1500
alk: always a bit low, around 6.5 (I'm working on it)
ca: always a bit high, around 475 (working on this too)

 

[spinoleo]

what test kits are you using

 

[jacksonpt]

all salifert

 

[spinoleo]

what are you dosing to keep your cal and alk up?do you dose kalk?

 

[jacksonpt]

I only dose alk... brs 2part via a dosing pump.

 

[Gary Majchrzak]

people always want to blame the lighting

people always want to blame the lighting

and here's a case where's it's legit.

This is a case where lighting is almost 100% certain causing the change in your coral's coloration. Why not move this higher undata back down lower... unless you like the new coloration?

 

[jacksonpt]

and here's a case where's it's legit.

This is a case where lighting is almost 100% certain causing the change in your coral's coloration. Why not move this higher undata back down lower... unless you like the new coloration?

I did today... again, just trying to identify/isolate variables. Often times what we think we see happening isn't what's actually happening, which is why I posted this thread.

additionally, I was skeptical that what seems to me to be relatively low light could be causing problems with most every sps I've tried aside from basic monti caps.

 

[Gary Majchrzak]

IME many Montipora species don't appreciate the bright lighting that many Acropora species require to thrive....

 

[SkiFletch]

If you ask me, it's a compound problem you're experiencing. Low alk along with PO4 (it's there with the algae) is rough on stony corals. Add some excess light stress and yeah, bleaching sounds right. I'd GUESS that if you could have your chemistry more-better, you might do better with moving corals to higher light.

 

[jacksonpt]

If you ask me, it's a compound problem you're experiencing. Low alk along with PO4 (it's there with the algae) is rough on stony corals. Add some excess light stress and yeah, bleaching sounds right. I'd GUESS that if you could have your chemistry more-better, you might do better with moving corals to higher light.

that makes sense... kind of a straw that broke the camel's back thing.

 

[Gary Majchrzak]

at this point we should not generalize about "corals"

at this point we should not generalize about "corals"

doesn't M. undata prefer less intense lighting?
(I never had this species)

Many Montis are touchy with coloration...

 

[jacksonpt]

IME many Montipora species don't appreciate the bright lighting that many Acropora species require to thrive....

good to know that it's fairly common among monti species. I've seen similar things happen with millis in the past as well, fwiw.

 

[Gravesj1s]

The salifert alk kits can be off as much as 2 full points.I personally would shoot for 9 to be safe but that's just me.

-Steve

 

[Gary Majchrzak]

I agree bump alk

I agree bump alk

Montis are sensitive to low alk but in this case both undata are sitting in the same water, right?
In other words... water can be eliminated as a variable here

 

[dreaminmel]

Are you using the same container for test water every time or a fresh and clean one? Reusing a container with deposits has thrown off my results before.

 

[Conesus_Kid]

My undata is at the bottom and is partially shaded by a monti cap. The shaded portion has better color, so I'd put my money on too much light in this case.

 

[jacksonpt]

Montis are sensitive to low alk but in this case both undata are sitting in the same water, right?
In other words... water can be eliminated as a variable here

Correct, both are in the same water, which is why I was hesitant to blame water conditions (at least as the sole factor).

 

[jacksonpt]

Are you using the same container for test water every time or a fresh and clean one? Reusing a container with deposits has thrown off my results before.

Same containers, but rinsing/drying them after each use.