Red macroalgae fading/bleaching?

[rrubberbandman]

Hi all,

So I have a very large healthy macroalgae but over the past few weeks it has decided to fade on top?

The only thing I did was switch a t5 bulb from a ATI coral plus to the purple plus.....Would this be the reason?

Thoughts?

[Origami]

How is everything else doing? Are there any other changes that might affect nutrient availability in the water? How old were your old lamps? Corals can sometimes bleach when new (fluorescent) lamps are installed because the old lamps dimmed and (they say) had some spectrum shifting. This might be part of it, but it's hard to say if there's a connection between brighter (not lower) lights and macroalgae turning white. (Obviously, I'm not a macroalgae expert. Just probing for discussion.)

[rrubberbandman]

13 hours ago, Origami said:

How is everything else doing? Are there any other changes that might affect nutrient availability in the water? How old were your old lamps? Corals can sometimes bleach when new (fluorescent) lamps are installed because the old lamps dimmed and (they say) had some spectrum shifting. This might be part of it, but it's hard to say if there's a connection between brighter (not lower) lights and macroalgae turning white. (Obviously, I'm not a macroalgae expert. Just probing for discussion.)

Everything else seems happy. Lamps were replaced in September.

 

[Origami]

Just to test if it's renewed light intensity, do you have any window screening material available that you can use to cut back the light entering the tank? Or can you raise the light some to effect the same change?

 

When I see plants changing color like that, I tend to think it's either a lack of nutrients or light. The OEM spec on the spectrum doesn't change much from the Coral Plus to the Purple Plus lamps. And, unless there was a notable shift in spectrum with the new lamps, you wouldn't think it would be that.

 

Possibilities that I see include:

 

Low nutrients: If your corals are uptaking more because of the increased light availability, maybe your nutrients have decreased and the plant is reacting to that. Or something else is going on that shifted nutrients. Have you seen an increase in any other part of the aquarium (e.g., green algae) that might compete for nutrients?  

 

PAR shock: Maybe the plant needs to adapt to the new, brighter light. This is more likely and easy to test by cutting back the light and slowly bringing the brightness up over a couple of weeks.

 

Low PAR: Ruled out with new lamps.

 

Spectrum shift: Unlikely as the spectra are almost identical with these two lamps (according to the OEM). 

 

 

[rrubberbandman]

23 hours ago, Origami said:

Just to test if it's renewed light intensity, do you have any window screening material available that you can use to cut back the light entering the tank? Or can you raise the light some to effect the same change?

 

When I see plants changing color like that, I tend to think it's either a lack of nutrients or light. The OEM spec on the spectrum doesn't change much from the Coral Plus to the Purple Plus lamps. And, unless there was a notable shift in spectrum with the new lamps, you wouldn't think it would be that.

 

Possibilities that I see include:

 

Low nutrients: If your corals are uptaking more because of the increased light availability, maybe your nutrients have decreased and the plant is reacting to that. Or something else is going on that shifted nutrients. Have you seen an increase in any other part of the aquarium (e.g., green algae) that might compete for nutrients?  

 

PAR shock: Maybe the plant needs to adapt to the new, brighter light. This is more likely and easy to test by cutting back the light and slowly bringing the brightness up over a couple of weeks.

 

Low PAR: Ruled out with new lamps.

 

Spectrum shift: Unlikely as the spectra are almost identical with these two lamps (according to the OEM). 

 

 

Great info....will explore some ideas. Calcium was low, probably due to us being gone for 3 days. Tank sitter just replenished evap. water.

Water change in the works.

[Origami]

Moving to General Discussion forum for the benefit of a wider audience.