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Related FAQs: Green Macro-Algae, Green Macro-Algae 2Green Macro Algae 3Green Macro-Algae 4, & Chlorophyte Identification, Green Macro-Algae ID 2, Green Macro-Algae ID 3, Green Macro-Algae ID 4, Green Macro-Algae ID 5, Green Macro Algae ID 6, Green Macro Algae ID 7, Green Macro Algae ID 8, Chlorophyte Behavior, Chlorophyte Compatibility/Control, Chlorophyte Selection, Chlorophyte Systems, Chlorophyte Nutrition, Chlorophyte Disease, Chlorophyte Reproduction/Propagation, Green Algae Control 1, Green Algae Control 2, Green Algae Control 3, Green/Hair Algae Control 4, Green/Hair Algae Control 5, Green Algae Control 6, Green Algae Control 7, & By Genus: Bryopsis & Derbesia, Bubble Algae (Boergesenia, Dictyosphaeria, Valonia...), Caulerpa Compatibility/Control, Caulerpa Compatibility/Control 2, Chaetomorpha, Halimeda, Neomeris, Hair (Filamentous, Attached) Algae, Green Water  (Planktonic) Algae Blooms, & CaulerpasCaulerpa 2, Caulerpa 3Caulerpa 4Caulerpa Identification, Caulerpa Behavior, Caulerpa Compatibility/Control, Caulerpa  Selection, Caulerpa Systems, Caulerpa Nutrition, Caulerpa Disease, Caulerpa Reproduction/Propagation, Green Algae Control 1Marine Algae ID 1, Marine Algae ID 2, Marine Algae Control FAQs II, Marine Algaecide Use, Nutrient Limitation, Marine Algae Eaters, Culturing Macro-Algae; Controlling: BGA/Cyano, Red/Encrusting AlgaeBrown/Diatom Algae

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/The Conscientious Marine Aquarist

Macro Green Algae, the Larger Chlorophyta

By Bob Fenner

Neomeris annulata 

New Print and eBook on Amazon

                                         Marine Aquarium Algae Control

by Robert (Bob) Fenner

Imagine having all the resources, time and money to do exactly as you please. What would you do? If you inherit or win the lottery, give me a call. I'll be your personal dive-caddy, accompanying you to all the places in the world where the water is warm and clear. Yep, if I were independently wealthy, I'd go traveling, diving the world's aquatic environments.

When most people picture entering the underwater world of tropical reefs, images of corals, rock, anemones and colorful fishes come to their minds. Is this realistic? Take a look around next time you're in the tropics, or at underwater pictures with an expansive view. Most of what's below the water is... water.

Taking a look at the living things, doesn't something seem amiss? I mean, compared with the land, are there more animals than plants? On closer inspection you'll find there is plenty of photosynthesis going on, and necessarily so. The phytoplankton suspended below the surface and throughout the lighted water column, and endosymbiotic algae are everywhere, and active metabolically. Less obvious in most cases, but still important are the sessile, or attached micro-colonial and macro-algae.

The strangeness of "why" there seem to be so relatively little "primary-producers" (photosynthetic plants, algae) compared with "consumers" (e.g. fishes and others) can be explained.

First I'll make a boring and shocking statement: Things are different in aquatic versus terrestrial systems! Boring because of course you know lots of ways their different. Shocking in the realization of how dynamic life on the reefs is.

It never fails to amuse me to read how "nutrient poor" tropical reefs are. Can you imagine the reasons for this? Obviously there is a tremendous amount of "fixed carbon" (i.e. living biomass) and flow of energy (everything eating and being eaten) going on; so why is the water considered "nutrient poor"? I'll tell you why; because those nutrients are jealously bound up by all the life around, and otherwise diluted by the oceans' volumes. They're not "nutrient poor", but nutrient "concentrated".

Look again at a reef, up close. What do you see? The algae there grow very quickly, but none look intact, or really vigorous. How come? They're continuously grazed upon. In experiments where algal feeding is restricted by fencing the area and removing algal predators, the algae take over the surface in short order.

What do you understand from the previous? Algae are a fast-growing, apparently important part of the natural reef. In a "balanced" setting their proliferation is kept in check by competition for scarce nutrient and perpetual grazing. Okay, me too.

For Aquariums:

This information can be of use to you in setting up and maintaining a marine system with more or less ease. Wouldn't it be great to strive for "a slice" of a real ocean environment in a captive system? Well, maybe not. Think about it; even if you had a humongous (let's say one thousand gallon) size tank, most of the space would be taken up by just the water, with actually very little rock, coral, and almost no macro-life at all. No, our captive seas are purposely over-crowded, hence over-fed/infused with nutrients, and therefore a struggle/challenge to keep balanced in our favor.

Even in such cramped, small quarters would growing some algae help? Decidedly yes. They aid in bio-filtering, removing/concentrating nutrients, making the same unavailable for undesirable forms of life, act as food and shelter, and hey, they look good.

Contrary to some reports macro-algae are not difficult to keep or culture. You don't need a tremendously sophisticated filtration system and a Doctorate in chemistry.

Most of the live algae you can buy are Greens (Division Chlorophyta), though most of what is stated here applies to all macro-algae species. The next Section on Brown (Division Phaeophyta) algae lists some techniques for collecting and mail ordering algae should you have no local source. Live algae can be easily be brought into a system by simply placing a small piece of "live-rock". The following expands on the benefits of macro-algae and lists their captive living requirements.


1) Bio-filtering: Macro-algae can aid considerably in establishing and stabilizing new or "out-of-whack" systems. They bring in and help to institute micro-organism communities, absorb nutrients introduced by food, decor and tap water. For systems with invertebrates, particularly anemones and live corals, live plant material can be especially helpful in improving water quality. In sufficient growing strength, macro-algae will remove nitrates, assist in buffering pH, uptake carbon dioxide producing oxygen, and assist in balancing trace elements (e.g. magnesium, phosphate, iron)

To some extent they are useful as bio-indicators; real-time monitors of the viability of the system. If your macro-algae will not live and grow, or start dying back, it is a warning sign that something is out of kilter chemically, physically and/or biologically.

2) Algae Control: Having a batch of algae intentionally growing in the system will go a long way in limiting the growth of unwanted forms (slime, string algae, fungus and bacteria) by competing for light, space and nutrients. For you reef-keepers, be aware that over-zealous algal growth may affect coral health through nutrient competition, smothering and possibly metabolite poisoning.

3) Food: Many, if not most of the marine fishes and invertebrates we keep augment their diets with large algae. What better deal than to have some continuously available for casual munching? Similar to our own nutrition, many trace nutrients make their way through this cycle.

4) Habitat/Ornament: macro-algae serve to break up the physical environment, affording hiding space from tank bullies and aquarists, and piece of mind to the inhabitants. Beyond this, they are aesthetically attractive; sheer beauty in terms of color, shape, size and motion.

Living Requirements:

For you folks with previous experience this will be very familiar turf. If pressed, you could write a parallel for using live aquarium plants in freshwater; so, what it takes to keep and grow marine algae are:

A) An established cycled, stable environment with "typical" conditions (high, steady pH; 1.021-1.025 specific gravity...) Synthetic water is fine. How can you tell when you're ready? Some of those "other" noisome micro-algae will have appeared on the scene.

B) Adequate nutrient levels; that probably do not require augmentation. You've been cautioned re the lack of need to replenish major and minor trace materials. Normal maintenance, including feeding should provide enough chemical nutrient. Adding more with metal halide lighting, carbon dioxide infusion, et al. might very

well boost growth, of macro- and micro-algae; with other, unwanted consequences.

Without adding any supplements, your algae won't die, it just will not grow as fast. Several of the authors in the bibliography below caution against too much macro-algae population and "pushing" these with additives. Algal metabolism can sway pH and other parameters, and even result in livestock loss.

You are warned again, concerning putting medications in your main system. Don't do it! Seek alternate treatment modes, dips, or best, a separate tank/system without algae or invertebrates.

C) Enough light, quality, quantity, and duration-wise. That is, balanced, full-spectrum, twelve plus hours per day, 2-4 watts per gallon. (please see Section 3) B) re lighting)

D) Being careful to limit mixing species of tangs, angels, butterflies, crabs, snails and others that relish destroying and devouring macro-algae.

E) Moderate, continuous water flow, stimulates growth and keeps debris off your algae.

What's Available:

What used to be considered the best: Caulerpas. Ask about sports cars and you hear Porsche, oak-ey wines and it's got to be chardonnay; for saltwater plant material the winner by a tank-slide are the Green algae species in the genus Caulerpa... though, yes, they can be toxic if grown too much, too fast, in the absence of decent filtration and maintenance. Unfortunately, Caulerpaceans have proven to be problematical, producing at times, copious amounts of undesirable chemicals, and worse, "going ballistic" reproducing sexually and polluting even large systems. Much better are the genera Gracilaria and Chaetomorpha (below)

Other Good/Useful Species:

In the trade are the true "old-timers" having been sold out of Florida since the fifties; that's 1950's, I'm not that old.



Anadyomene stellata. St. Thomas 2014

Bryopsis plumosa, a common pest algae in captive marine systems. Note feathery appearance of thalli. Greatly enlarged here. 

Verticals (Full/Cover Page Sizes Available)

Caulerpas by Bob Fenner, A closer look at Caulerpa - Common aquarium species and their care by Adam Jenkins,
Chaetomorpha spp. An exemplary genus for multiple marine hobby uses... Pic by MichelleL.

Chlorodesmis fastigiata, Turtle Weed. Found widely in the South Pacific and marine aquariums. Prefers brisk water movement and bright light. Can be a pest if too prevalent, otherwise useful for nutrient uptake/consolidation, food for some tangs and angelfishes; toxic to some corals in proximity. Considered by some as host/food for the Nudibranch Cyerce nigricans. Fiji image.

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Halimeda (FAQs) species are crusty, calcified algae that look like a bunch of small platelets strung together in a chain. They are good choices if you have a lot of grazers, as it is tough to chew. Pictured below: the genus in the Bahamas, in a saltwater tank, and in fifty feet of water in Fiji. At right: Halimeda opuntia off of Cancun, Mexico. 

Halimeda copiosa. Long chains of rectangular segments, linked together with thin central element. St Thomas 2014.
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Halimeda discoidea, Large Leaf Watercress Alga. To eight inches tall, 1" segments. Disk-like segments joined by flexible joints. A commonly occurring species in the tropical West Atlantic, and extensively used in marine aquariums. Bahamas pic.

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Halimeda goreaui, Small Leaf Hanging Vine. Tropical West Atlantic. To a foot in length, segments to 1/4" diameter. Chains of small, three-lobed segments. Grow in subdued lighting. Bahamas pic. 

Verticals (Full/Cover Page Sizes Available
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Halimeda macroloba N. Sulawesi images of healthy and calcium carbonate skeleton remnant colonies. 

Halimeda monile 3-8 inches tall. Here in Jamaica.  

Halimeda opuntia, Cactus Coralline Algae. Batches to about 15 cm. in width. Here in Raja Ampat 08.

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Halimeda tuna, Stalked Lettuce Leaf Alga. To ten inches in height, 3/4" segments. Tropical West Atlantic. Stalked uniplanar colonies which branch as they grow outward. Cozumel image by Di.F.

Neomeris annulata, Caterpillar Weed, Fuzzy Tip Alga. Below: Aquarium, Cozumel and N. Sulawesi close-up images. 

Penicillus dumetosus, Bristle Ball Brush. Tropical West Atlantic. To six inches in height. Belize, Cozumel and an aquarium specimen shown below.

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Penicillus pyriformis, the Merman's Shaving or Flat-Top Bristle Brush is a tuft of bristles rising out of a vertical stalk. Take care to gently place these in fine sand. Cozumel pix including typical sandy habitat. 

Rhipocephalus phoenix, Pinecone Algae. To five inches in height. Look like pinecones of sorts, with overlapping thalli growing outright from a single, attached stalk. Cozumel image. 

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Tydemania expeditionis Weber-van Bosse 1901, which I like to call "Dread-Locks Algae", for obvious reasons. In Fiji, Red Sea, N. Sulawesi.

Udotea looks like a soft green fan(s), some individuals having more than one. Two views of shallower water and older, deeper water colonies in the Bahamas and a grouping in Cozumel.

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Udotea cyathriformis, Mermaid's Tea Cup. To six inches in height. Thin walled cups attached to a single stalk. Easily torn in handling. Tropical West Atlantic in shallow sandy bottoms and coral rubble zones. Cozumel image by Di.F.

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Ulva, Sea Lettuce, this and related Enteromorpha are great fish foods.

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Pest Green Algae Species... Greens that grow too fast, obnoxiously in marine aquariums...

Defined as such by simply being too much of something... overgrowing more desired life forms, utilizing too much nutrient intended for same, possibly producing allelopathogens (substances that disenfranchise other life), or just being too plain, too much that nothing eats..., outside of our value systems. There are many types of these Green Algae. Here's a line-up of most commonly encountered scourges.

Bryopsis, a worldwide genus of Greens that appear filamentous to spiky in aquariums... light to dark green, generally feather-like thalli. Some Hermit Crabs, Blennies, Zebrasoma and Ctenochaetus Tangs may eat your type... otherwise, scrubbing, competitive algae filtration are recommended.

Chlorodesmis fastigiata, Turtle Weed... common in the wild, common in marine systems with inadequate competition, available nutrients, lack of circulation, filtration... A couple of shots in the wild: Fiji, the Andaman Sea.

Derbesia, another worldwide temperate to tropical pest Green (for aquarists) similar in treatment as Bryopsis. Presents itself as a prostrate basal portion with erect subdichotomously branched filamentous  portions above... Here in an aquarium.

Dictyosphaeria cavernosa. See Valonia below. Shots in Belize and Hawai'i.

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Valonia macrophysa, Elongated Sea Pearls. To 3/4" in diameter. Spherical to elongated shiny "balls" of silvery appearance that grow in clusters. Here in Cozumel. 

Valonia (Ventricaria) ventricosa is often noted as the "largest single-celled alga" reaching a hen's egg in size... but it is actually a multinucleate vesicle held down by attachment rhizoids. Dictyosphaeria species,  in the same group, Order Siphonales, are similar with polygonal vesicles, versus lenticular ones for Valonia.  Mithrax/Emerald Green Crabs may eat these. 

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Friend (Dr.) Myron Roth absolutely amazed at the prospect of clearing a giant bubble algae. Actually a plexi dome at an exhibit at the Shaw Centre in Victoria, B.C. 2010! 

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An unknown green algae encountered in Cozumel 2012.
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Bibliography/Further Reading:

New Print and eBook on Amazon

Marine Aquarium Algae Control

by Robert (Bob) Fenner

Baugh, Thomas M. 1988. Caulerpa prolifera; an attractive species which does well in the marine aquarium. FAMA 5/88.

Brawer, Marc. 1971. So you want to keep marine plants. Marine Aquarist 2(2):71.

Brelig, Allen. Plants in the reef system. FAMA 6/93.

Caribaldi, Lou. 1973. Seaweeds are not weeds. Marine Aquarist 4(4):73.

Delbeek, Charles J. 1990. Live rock succession in a reef system. FAMA 10/90.

Giovanetti, Thomas A. 1989. Caulerpa enemy of the miniature reef aquarium? FAMA 10/89.

Hoff, Frank. 1988. Coral reefs of Florida, part II; the algae. FAMA 1/88.

Hoff, Frank H. 1983,84. Marine algae of the genus Caulerpa, parts 1,2. FAMA 10/83, 4/84.

Jacobs, William P. 1994. Caulerpa; this tropical alga is the world's largest single-celled organism. yet it differentiates into a complex structure of leaves, stems and roots. Scientific American 12/94.

Kraft, Herbert. 1959. A step forward for marine aquarists; Caulerpa prolifera, a plant for salt-water aquaria. TFH 5/59.

Mancini, Alessandro, translated by Paolo Macedone. 1995. Tropical algae of the genus Caulerpa Lamouroux, 1809. FAMA 6/95.

Mayland, Hans J. 1975. The leafy algae, Caulerpa prolifera. Marine Aquarist 6(4):75.

Minor, K.I. 1995. What is that? part II: Valoniaceae. FAMA 6/95.

Smit, George. 1987. The ecological marine aquarium, part four; the use and benefits of live rock and Caulerpa in marine aquariums. FAMA 8/87.

Sprung, Julian. 1989. responding to questions re the sexual reproduction of Caulerpa in captive systems. FAMA 2/89.

Thiel, Albert J. 1988. Keeping and growing marine macro-algae. FAMA 8/88.

Tullock, John H. 1983. Growing marine 'plants'. FAMA 3/83.

Wilkens, Peter. 1992. Green water in the aquarium; the sexual reproduction of Caulerpa algae. TFH 2/92.

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