Dear wam:
The one concern that some aquarists have regarding Caulerpa are the substances it can release into the water when it enters its reproductive phase, as described below:
When Caulerpa goes sexual, it enters a different stage of life. All of the mature Caulerpa will die back at once, literally disintegrating in a matter of moments after they release their reproductive products, turning the aquarium milky white in the process. This can be unsightly and alarming, but in a well-filtered aquarium it’s more of a nuisance than a disaster. The nutrients it releases into the water upon disintegrating are primarily phosphates and nitrates, which are undesirable since they promote the growth of nuisance algae but are not toxic in themselves, and the resulting cloudiness clears up within a matter of an hour or two in an aquarium with adequate filters — sooner if the tank is equipped with a protein skimmer and chemical filtration. Some Caulerpa can released toxins during these vegetative events, but activated carbon will remove these as fast as they are produced. Regularly pruning back the Caulerpa is an effective way of preventing it from going sexual and removes excess nutrients from the aquarium.
In short, I feel the benefits of well-maintained Caulerpa normally far outweigh any potential risks and the aquarist can easily control it and prevent it from going sexual by routinely thinning out the colony. However, some exudations released by some Caulerpa at other times can be harmful to delicate corals over the long run, if not controlled by regular water changes and proper filtration.
So I can certainly understand your concerns, wam. You may not be confident that you’ll know when the Caulerpa needs pruning or you may be unsure of your ability to trim it back properly.
If you have any doubts in that regard, or you’d simply prefer to play it safe and not expose your prized ponies to any potential risk from the Caulerpa, however slight that may be,
some of the other macroalge you may wish to consider instead are Gracilaria, Ulva, Chaetomorpha, and Chlorodesmis. Hawaiian Ogo (Gracilaria sp.) are bushy red-to-brown macros that also do well under low light levels. Sea Lettuce (Ulva sp.) are deep green sheets of algae that do best under a little stronger lighting. Maiden’s Hair (Chlorodesmis sp.) are bright green tufts or clumps of very fine-bladed algal mats to grow attached to small rocks. All of these types of macroalgae are much less prolific and slower growing than Caulerpa. However, like all macroalgae, they should still be harvested periodically in order to export the excess nutrients they have consumed.
Aside from red and brown Gracilaria and the bright green Ulva and Maiden’s Hair, some members of the group also like the Chaetomorpha turf algae from http://www.floridapets/. They describe it as looking like the clumps of the colorful plastic grass we use to fill Easter baskets. They like it because it is slow growing and doesn’t require the kind of pruning that Caulerpa needs, and because it it comes loaded with microfauna: miniature feather dusters, copepods and amphipods, tiny snails and micro stars. Sounds like another interesting marine plant that can add some extra variety to a lush bed of macroalgae.
But if I was you, I would just keep the Caulerpa and allow it to act as an excellent form of natural filtration, reducing the available levels of phosphates and nitrites/nitrates,.and be sure to prune and trim it back regularly. When you remove the excess Caulerpa, you’re exporting phosphates, nitrates and other nutrients from the tank, thereby helping to maintain good water quality, and pruning the runners is a simple way to keep it from going sexual.
When pruning or trimming back macroalgae, take care not to actually cut it. Remember, you’re not pruning hedges or trimming trees — the idea is to carefully pull up and remove continuous, unbroken fronds. Simply thin out the colony of excess strands, gently plucking up convenient fronds that can be readily removed intact. A little breakage is fine, but cutting or breaking too many strands will result in leaching undesirable substances into the aquarium water as the Caulerpa’s lifeblood drains away. Too much cutting or breaking can thus sap the colony’s strength and cause die offs or trigger the dreaded vegetative events that judicious pruning otherwise prevents.
Best of luck with your macros, wam!
Happy Trails!
Pete Giwojna
Ocean Rider, Inc. is an Organic Hawaiian-Based Seahorse Aqua-Farm & Aquarium that Follows Strict Good Farming Practices in Raising Seahorses and Other Aquatic Life.
