Halimeda getting white - going sexual 3/11/04
Hello Anthony!
<cheers, Thanassis>
In my display tank, as well as in my sump, I have macroalgae growing (Dictyota, Halimeda and  a little Caulerpa racemosa).
<please do resist mixing macroalgae species... they will not fare well together in the long run (competition and chemical aggression)>
During the last couple of days I noticed that some -not all- of my Halimeda has turned white - I mean totally white colour. Does this mean it is dead?
<sort of... it may simply have gone sexual and new growth will sprout in the system in the next couple of months. Else, it has suffered from the very toxic/noxious Caulerpa racemosa (one of the most noxious of all macros in the sea)>
If yes, should I remove it from the tank?
<you can let it dissolve and provide calcium. Also do a large water change>
I checked my Ca Hardness is 11 dKH and Ca is 450. What could be the reason of this problem?
<no problem at all here>
Thanks, Thanassis
<best regards, Anthony>

Halimeda Turning White?
Hi, can you help me out with this question?  My Halimeda is turning white. What does this mean?  Thanks. Mike
<Well, Mike, as you probably know, Halimeda is a calcareous algae, which takes calcium from the water much as corals do. This algae will turn white during part of its life cycle, and drop its platelet-like "leaves" during this phase, in many cases. This is quite normal, in my experience. Remember, Halimeda is responsible for producing lots of aragonite material in nature, so there's nothing wrong with the "leaves" remaining in the system, in my opinion, should they fall. Also, I have noticed that the leaves will turn white in the dark, and then return to their normal green appearance when light returns to normal levels during the day. Sporulation (part of the reproductive life cycle) with this macroalgae does occur, but I'll bet that this is not what you're seeing. If you maintain normal "reef" levels of calcium in your system, you will enjoy long-term success and continued growth with this macroalgae. Just don't give up on it, and you should be successful with it. Under the proper conditions, this is a highly prolific and desirable macroalgae! I love this stuff! Good luck! Regards, Scott F>

Size of Penicillus,  Rhipocephalus,  related taxa
<cheers, Peter>
I am curious as to the maximum size of the "striped" algal taxa like Penicillus and Rhipocephalus. In my reading,  I have noted reports up to 1 meter,  but in my personal experience have never seen any representatives of the striped taxa nearly that large.
<agreed from the perspective of my travel/diving and aquaristic endeavors>
My interests are not for aquarium growth,  but for comparing fossil algal taxa to recent striped forms.  I am looking for a recent example which might have a stipe approaching 10-12mm in diameter and a stipe length of as much as 20cm.  Can you help at all? Peter Giles Senior Appalachian Geologist
<alas, Peter... I wish I had an addy for the Littlers for you. We can perhaps dig one up when Bob returns from NY. In the meantime, have you consulted their works?
http://www.seachallengers.com/index.cfm?catID=5
really outstanding: http://www.seachallengers.com/index.cfm?catID=5&itemID=280
and for great natural history books in general the home page:
http://www.seachallengers.com/
best regards, my friend. Anthony>

Halimeda gone sexual 6/3/03
Good morning:
<Howdy>
Overnight my Halimeda seems to have been attacked by red and green spots (in the terrestrial world I would call them spider mites) turning the plants white and the water has gone cloudy.
<what has happened is that they have gone from being vegetative... either from a stress (newly acquired, or recently stress from a temperature or salinity change, e.g.)... or from a period of vigorous growth without adequate pruning which has allowed the colony to go sexual/mature>
No fish currently in residence as they are in ick quarantine but my polyps remain as do the crabs, snails and LR. Should I be ripping the Halimedas out of there and what could be attacking them?
<the bleached colonies are dead. New colonies are likely to sprout in the tank within months. Remove the dead matter and conduct a large water change. Use fresh carbon too>
Thanks as always for your assistance. Charlie
<kind regards, Anthony>

Green seaweed research questions (and useful, scientific input!)
Hi Bob,
I found your address at the WetWeb site and thought I'd contact you directly. Hope you don't mind.
<Not at all>
I'm a bio professor/researcher who studies the reproductive behavior of tropical green algae in their natural environments (Halimeda, Caulerpa, Penicillus, etc). I notice a fair number of posts to aquarium sites that have to do with "green clouds", "white" or "dying seaweeds",
etc. and recognize (as you do) that most of this relates to the sexual reproduction of these seaweeds... a 24 hour conversion from sterile to fertile condition, followed by explosive gamete release at dawn and immediate death of the "parent".
<Yes.>
My research explores the consequences of these reproductive events on coral reefs (mostly Caribbean, though I'm currently on sabbatical in Guam). I'm particularly interested in what induces a seaweed to become fertile, since we often find hundred to thousands of algae on a reef (but
never all of them) becoming simultaneously fertile... not only is the ensuing bout of sex the next morning a spectacular visual phenomenon..
the subsequent death of so many "adult" seaweeds has important ecological implications for the reef community as a whole.
<Agreed>
I notice from various posts within the aquarium trade that lights, chemistry, temperature, stress, etc, etc, are implicated in the onset or prevention of reproduction by green seaweeds in aquaria. Do you know of any formal treatment of this idea... 
<No... unfortunately seem to be entirely anecdotal accounts... of "stress", change that bring on these events.>
or is it just a hodgepodge of observations thrown out over time? I notice you reference "24 h" lighting as a preventative and I've seen reference to blue lights, or
non-blue lights (can't remember which) having similar effects. If you're interested, I'd love to pick your brain about this... or you can sic me on someone else.
<Very glad to be of assistance.>
If interested, you can also learn more about my research on seaweeds by visiting: http://lclark.edu/~clifton/Algae.html
<Thank you much for this reference. Will post to our sites (WetWebMedia) for hobbyist perusal>
Thanks for your time... I hope to hear back from you.
Ken Clifton
<Sorry for the delay in response. Have been on a liveaboard... in the Bahamas. Be chatting, Bob Fenner>

Green Algae
Greetings!
<<And greetings to you - JasonC here...>>
First let me thank you for the always great advice and prompt responses. I know I really appreciate it a lot. I read the FAQ's almost daily to try and increase what little knowledge I have :-). I have 1 question for you. <<Go for it.>>
Here is my setup:
75 gallon tank
Emperor 404 with 3 carbon packs and 1 Nitra Zorb
1 Skilter 250 retrofitted with limewood stone for protein skimming
2 oscillating 214 powerheads
70+ lbs live rock
80 lbs live sand
6 green Chromis
1 striped damsel
1 dragon goby
1 spotted cheek tang (related to Kole tang)
1 Pacific Blue tang
3 turbo snails
1 sand sifting starfish
<10 small hermit crabs
1 small Xenia coral (Waving hand)
1 group (20-25) green button polyps
1 40w actinic (sunrise sunset)
2x 110 10k Aquasun VHO and 1 110 watt actinic (10 hours on @ 370 watts total)
My question is this. I keep getting a "film" of some sort of green algae on my glass. When I clean it with the magnetic cleaner, it looks "dusty" on the inside. I could do this once every two hours and still not keep up. I have been told by my LFS that it is a "phase". I don't overfeed and all my readings are fine (78 degrees, 0 ammonia, 0 nitrate, 5 nitrite, 8.3-8.4 PH) with weekly 8-10 gallon water changes. Is there anything I can do to alleviate this or am I just going to have to clean my tank forever? <<I would agree with your LFS and say this is a phase - could be the tank is getting some sun during the day? This is often a factor... but yes, glass cleaning is part of the normal maintenance.>> And everyone in my tank gets along GREAT!! <<Glad to hear it.>>
Thanks again for all the help! Richard Riedling II
<<Cheers, J -- >>

Green Algae (Take II)
Greetings!
<and salutations to you>
First let me thank you for the always great advice and prompt responses. I know I really appreciate it a lot. I read the FAQ's almost daily to try and increase what little knowledge I have :-). 
<and share your knowledge in kind>
I have 1 question for you.
Here is my setup:
75 gallon tank
Emperor 404 with 3 carbon packs and 1 Nitra Zorb
1 Skilter 250 retrofitted with limewood stone for protein skimming
2 oscillating 214 powerheads
70+ lbs live rock
80 lbs live sand
6 green Chromis
1 striped damsel
1 dragon goby
1 spotted cheek tang (related to Kole tang)
1 Pacific Blue tang
3 turbo snails
1 sand sifting starfish
<10 small hermit crabs
1 small Xenia coral (Waving hand)
1 group (20-25) green button polyps
1 40w actinic (sunrise sunset)
2x 110 10k Aquasun VHO and 1 110 watt actinic (10 hours on @ 370 watts total)
My question is this. I keep getting a "film" of some sort of green algae on my glass. When I clean it with the magnetic cleaner, it looks "dusty" on the inside. I could do this once every two hours and still not keep up. I have been told by my LFS that it is a "phase". 
<if the tank is less than 4 months old then the diagnosis is not only possible but likely! And regardless of the age of the tank, any such nuisance algae can be easily starved into oblivion with aggressive protein skimming. If you adjust your skimmer to produce daily consistent dark skimmate, your algae will disappear in 2-6 weeks>
I don't overfeed and all my readings are fine (78 degrees, 0 ammonia, 0 nitrate, 5 nitrite, 8.3-8.4 PH) with weekly 8-10 gallon water changes. Is there anything I can do to alleviate this or am I just
going to have to clean my tank forever? And everyone in my tank gets along GREAT!!
Thanks again for all the help! Richard Riedling II
<best regards, Anthony>

Algal succession
Hi again,
<howdy>
Suddenly my two month old tank is sprouting bright green spots on a lot of the rocks and coral skeletons. Any idea what they are and whether they are good or bad? 
<green microalgae... quite natural in the process of algal succession (brown algae is waning I assume)>
They are actually a beautiful, brilliant color so I'd hate to hear that they are a nasty thing that I must eradicate.
<if you control nutrients in the tank you can enjoy a nice luxurious growth of it without it taking over>
Ana M. Saavedra
<best regards, Anthony>