Oh, Not Another Problem – Sailors Eyeballs


Marine aquarists meet some problems along the way, some are more difficult to deal with, for example Aiptasia anemones often called glass anemones. Then there are the annoying problems such as the yukky algae (technical description that!) which is often caused by under-par sea water. The sailors eyeballs mentioned in the heading is another type of algae that sometimes finds its way into the aquarium and though not a high level problem it needs to be dealt with or it can become very annoying.

Sailors eyeballs are also known as bubble algae and sea pearls. The proper name is Valonia ventricosa. As can be seen, they are small and could perhaps be considered as attractive. Each bubble could be 1 to 4cm in size (.39 to 1.57 ins). They can grow singly but often grow in multiples against each other and on top forming a pile. The colour is light green or dark green though they can appear silvery. They can spread and will do so if not controlled. The overall marine aquarists opinion is to ‘get rid of’.

It would seem an easy way to get rid of the algae would be to squash it – not a good idea as it will spread with that assistance. If the algae is situated on glass or another reasonably smooth surface the whole pile can be removed by running a thin object between the algae and the surface making the bubbles easy to dispose of. If this cannot be done then there is a way of removing them safely. Obtain a length of flexible air tube and a short length of rigid air tube or plastic pipe which the air tube will fit onto tightly. The rigid tube should be of sufficient length to allow access to the whole aquarium and the flexible air tube long enough to reach a bucket on the floor. When the two are connected the aquarist tests by putting the rigid end into the aquarium and the flexible end into the bucket, then sucks quite hard on the end of the flexible tube. This will hopefully cause seawater to flow down the tube into the bucket. If so the sytem is ready. If not, is the flexible tubing too long?

When the algae cannot be easily removed, for instance it is on a rough surface rock etc, or in a crevice, the aquarist places the rigid tube in the seawater and sucks as described. When seawater enters the bucket the end of the flexible tube is squeezed closed causing the flow to stop. When the algae has been targeted with the rigid tube (don’t remove the tube from the seawater) the flexible airline is released and the flow of seawater resumes. The end of the rigid tube is placed onto the algae bubbles one at a time and they are burst by applying pressure. This could seem a slow process but it works. Apparently any spores that could be released by the algae causing regrowth are sucked out of the aquarium as the algae bursts. A good time to do this is before a partial seawater change as it assists in removal of seawater, though not to a large extent. The method can be applied anytime as the amount of seawater removed is minimal. The removed seawater should, of course, be discarded. As with problem anemones, checks for the algae can be made part of the aquarist’s routine.

At first the aquarist could consider that sailors eyeballs are decorative and welcome. However, as with most types of algae it spreads until it is very obviously excessive and spoils the overall beauty of the aquarium reef. It’s best gone.

(Photo: en.wikimedia.org)


  1. Never heard of those sailors eyeballs before. Have to admit that they are the most beautiful algae I have ever seen 😀

  2. Yes, it’s a pity they are problematic if the aquarist isn’t careful. Glad you visited Lisa call again.

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