Pete Giwojna

Dear arcprolife:

It’s a common misconception that all Sargassum are free-floating plants. That’s not the case at all, sir — there are many species and all have tissues differentiated into a holdfast, which anchors the plant on the bottom, stipes, fronds and fruiting bodies. And, of course, some species have the berry-like, gas-filled bladders that help to support the plants and keep them upright in the water column (Sargassum plants get to be several meters long). What often happens is that portions of these Sargassums will break free of the main plant and float to the surface. Such rafts of Sargassum can survive perfectly fine, afloat and drifting at the surface where they receive plenty of sunlight, until they eventually drift ashore. In areas where the prevailing currents bring these drifting mats of Sargassum together in the open ocean (e.g., the Sargasso sea), the floating masses accumulate and there are extensive floating populations of the seaweed.

Sargassum species are found throughout tropical waters around the world, where they grow subtidally attached to coral, rocks, or shells in moderately exposed or sheltered rocky areas or inshore pebble beaches, often forming dense beds or forests of Sargassum where conditions are favorable.

Although it is hardy enough, live sargassum is ordinarily not kept in home hobby tanks simply because it grows too fast and too large for a typical closed-system aquarium. As Anthony Calfo puts it, " Other species [of macroalgae] are quite sturdy but simply grow too large or too vigorously, like Sargassum, for most display tanks."

For this reason, most hobbyists will do better with the artificial Sargassum plants I recommended, which make ideal background decorations for tall tanks.

If you want to try some live Sargassum, arcprolife, you can obtain Sargassum on rock from Inland Aquatics at the following URL:

But if you want some shorter plants to complement the tall artificial Sargassum and rest on a rock pile, then I think you might like the "red-on-rock" algae species offered by Inland Aquatics more instead. They are more colorful and won’t overgrow or overwhelm your tank.

Maiden’s hair algae and sea lettuce (Ulva spp.) are bright green species of macroalgae that normally grow attached to rocks and are typically sold that way for aquarium use. They could also be placed on mid-your live rock where they would receive bright light.

If you are looking for marine plants to maintain in a sandy area of your tank, many species of Caulerpa, Merman’s shaving brushes (Penicillus spp), Udotea "sea fans," and Halimeda sea cactus are available, all of which are just anchored in the sandy bottom and will put out rhizoids or holdfasts to keep himself in place. Other species of Halimeda are available that sprout from live rock instead, so that’s another option if you prefer.

But the Halimeda sea cactus, Penicillus shaving brushes, and Udotea sea fans are all calcareous macros that require high levels of calcium in order to thrive. To maintain them successfully, you will need to monitor the calcium levels, total alkalinity, and carbonate hardness of your seahorse setup, provide occasional supplements of calcium or Kalkwasser, and maintain the aquarium more like a reef tank than an ordinary saltwater system.

Some macroalgae are rootless and do not anchor in place. This is true of the Chaetomorpha turf algae or spaghetti algae, for instance. It grows in tangled clumps that look like nothing more than the colorful green Easter grass we use in our Easter baskets as betting for the jellybeans, marshmallow chicks, and chocolate bunnies. Chaetomorpha is therefore not very aesthetic looking in your main tank, but you can’t beat it for use in refugia or algal filters because hordes of copepods, amphipods, and other microfauna love to shelter, feed, and breed in the tangled masses of the spaghetti algae.

Like the Chaetomorpha, different types of Gracilaria or Ogo are often cultured by tumbling them so that they are always in motion, exposing different areas of the plant masses to the sunlight and assuring that clean water circulates through them continually. Several different types of Gracilaria (red, brown, green) are available and are typically sold in clumps by the bag or the pound. They don’t have roots as such, of course, but if you wedge them in crevices in your live rock or anchor them in place with a small rock or piece of coral rubble, they will attach to a hard substrate and grow well under favorable circumstances. Again, like the Chaetomorpha, these balls or clumps of Gracilaria/Ogo are ideal for culturing copepods and amphipods in your sump or refugium, but they will also look nice in your main tank once they take hold.

You might like to try the Macroalgae 6 Pack from Indo-Pacific Sea Farms. It includes six different types of algae that grow well in the aquarium and have different colors — gold, red, green, brown, yellow, etc. — so it would make a colorful assortment to spiff up your aquarium and intermingle live plants among the artificial decorations:

Click here: Indo-Pacific Sea Farms

Best of luck with your macroalgae and tank decorations, arcprolife!

Happy Trails!
Pete Giwojna

Post edited by: Pete Giwojna, at: 2008/08/06 01:12

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