Red macroalgae bleaching

[Samala]

Every once in a while keeping a tank log with photos really pays off. We often hear about red macroalgae bleaching under high light, or read about it on the boards, but seldom do we actually see evidence for it happening.

Enter my latest tank. I just switched last month from 130w PC to 48w T5HO (both 10,000K) and apparently the red macroalgae think that its a LOT more light than they had previously.

While they have been growing very nicely (and soaking up quite a bit more NO3 and PO4 consequently) they have also bleached down to a pale pink.

Most of the macro in the photos below were just trimmed (excepting the Gracilaria that is), in particular the red macro 'bush' at the bottom center/right and the Caulerpa prolifera (which gets trimmed at least every other week if not every week).

Anywho, here's a nice example of bleaching going on:

April:

May:

Sorry the photos are a bit of a mess. I'm still learning new tricks with the camera, especially for compensating for glare.

>Sarah

 

[HowardW]

Did you switch from a single 130W PC bulb to a single 48W T5, and was the PC bulb very old? I ask because a 48W T5 shouldn't put out more PAR than a new 130W PC.

 

[Samala]

I wouldn't exchange brand new 65w x2 PCs for any light. The lights on the tank were about eight months old, so not terribly old but certainly past prime. It was a Coralife unit that was at least two years old, without really good reflectors.

The new lights are T5HO, overdriven, with great reflectors. Maybe they shouldnt be putting out more PAR, but they certainly do seem much brighter.

>Sarah

 

[HowardW]

Oh......if those PC's were 8 months old they were probably only putting out less than 1/2 of their original PAR, and if the overdriven T5s had good individual reflectors then they would definately put out a bunch more PAR than your old PC bulbs.

 

[kae]

Are you saying that only a single bulb of 48w T5HO is overkill for red macroalage? Actually I've never heard that T5HO has 48w bulb.

 

[Samala]

Its total wattage.. 2x24w T5HO. I didn't say they were overkill, I'm showing the reaction of macroalgae from lower light to higher light.

>Sarah

 

[kae]

Are that red macros dying or just bleaching? Thank you.

 

[kaptken]

It is quite possible the two 24 watt HO T5's are putting more useful light into the tank than the old pair of 65W PC's. Its all in the reflectors. flat, square type reflectors for twin tube PC's are very poor at getting all the light into the tank. there is a lot of strike back of light back into the tubes on the top. which loses half the light. where as the parabolic reflectors for T5's are very efficient at getting nearly all the light focuced down, into the tank. and if you say they are over driven, well, that is even more light. there might also be a difference in spectrum between the two types of bulbs. do you use an Ice Cap ballast?

Nice tank! Sarah. I have several types of red macros in various tanks, that come and go. depending. Reds are nice.

ken

 

[Samala]

Hey Ken, nice to see you around again. The reds are certainly fun, I agree. Yes, ice cap. So.. a spectrum shift? Really?

Kae: they are not dying, the bases of the algae remains the darkened coloration. As they are growing out they are getting lighter in coloration. Hence, bleached, in effect. Not a true loss of color though.

>Sarah

 

[Elite]

I have some red in my tank and most died when I upgrade my light from 250W to 400W MH. They are growing back though.

 

[kaptken]

Hi Sarah, yes , it's me. I've been browsing this forum for tips to set up a fuge with turtle grass and manatee grass for my 75 reef. I need something real agressive on nitrates and waste to starve out the the infestation of caulerpa verticillata I've had for a long time. I'm hoping those two grasses will do it. All my reds and some other caulerpa were hitch hikers on rock that i nurtured along. Oh Look, a new life form!! unfortunately, so was the verticillata.....

Yes, the ice cap will drive the 24 watt T5s at 40 watts each and put out a lot of light. I wasn't thinking of a spectrum shift as much as perhaps a different phosphor mix in the different brands of lamps. Might give a different spectrum of light. 10K's are not all created equal. and the T5 reflectors make a big difference too on the amount of light into the tank.

I enjoyed your recent articles in Reefkeeping magazine. Keep up the good work!

ken

 

[skeeter-doc]

Sarah, will the reds comtinue to bleach and then die? How/When will they come back to their former glory?

 

[Samala]

Maybe I should have used a better word. If you take a look between the two photos there is some evidence of growth, compare the heights of the algae (and its hard to see, but there is also a big difference in the depth of algae in the top left). The old parts of the algae are not 'bleached' out. What you're looking at in the difference in color is the algae that has grown under new lighting conditions, and has reacted to this change. Effectively they are bleached, but its a bad choice of word - they didnt lose any original dark coloration. That's just the color they are growing out with now.

Usually when macroalgae dies the entire algae, or at least large segments of it, bleach down to either a translucent or pure white coloration. The 'bleached' algae I have isnt translucent, and is still actively growing. I'll have to try to get a different set of photos up that show they're still alive and kickin.

Now, of course, you can shock algae with too much light. I know there's a thread here from me on Halymenia reacting with orange flourescence to too much light.

>Sarah

 

[awrieger]

Hello, new here. T5 phosphors I've been told are about 20-30% better than PCs anyway, then add decent reflectors and you've got much better light even at lower wattage.

That actually appears to me as a micro-nutrient deficiency. Strong but pale new growth is most likely iron deficiency. At least it is in FW plants. You'll need to up the nutrient dosage to match the new growth speed, in this case possibly Seachem Iron.

Although I've been doing some cram studying this last week to learn more (and have seen your CO2 seagrass tank), I have no experience with macro-algae, so take my advice with a grain of aquarium salt.

 

[WarEagleNR88]

<a href=showthread.php?s=&postid=9999164#post9999164 target=_blank>Originally posted</a> by awrieger
That actually appears to me as a micro-nutrient deficiency. Strong but pale new growth is most likely iron deficiency.

This is also my thoughts when I see normally colored plants turning a bleached color. That or something else, perhaps Iodine? It's hard to tell.