Hi Dave,
I use my 'local' Maidenhead Aquatics (Morden) as well and have generally been impressed with the stock and with the staff.
I have been looking at algae balls recently as well. I found a couple of bits of information:
Cladophora aegagropila, commonly known as Algae balls, Marimo Balls and "Tribbles"
As the name implies, this is an algae and not a true plant. It is non invasive and will not cause algae in your tank. Algae eaters seem to leave them alone as well.
Native to Lakes in Japan, it is considered a national treasure. They start by getting rolled around on the lake shores. Once round, they tend to stay that way. Most found in the aquarium trade will be an inch or two in diameter, however, there have been cases of them reaching a foot. These will be very old, and most likely hollow in the center.
Under high light conditions, during photosynthensis, they will float. At night they will sink back to the bottom.
Very slow growers in just about any tank conditions. Propigate by splitting in half. To help get the round shape back simply fold the flat part back together and hold in place with fishing line.
They do attract debris in the aquarium. Simply take it out and rinse as you would your filter sponge.
and another
Cladophora Balls!
There exists a very specialized form of Cladophora known in Japan as Marimo Balls.
These are free floating (or sinking), perfectly spherical colonies of Cladophora aegagropila, that can grow as large as 30 cm (1 ft) across. Cladophora balls have been observed in many parts of the world, but the only place these algae can be found now is in one lake in Japan, Lake Akan.
This species of Cladophora usually is found as a mass of filaments attached to rocks or floating freely at the surface of bays and lakes. The special hydraulics of Lake Akan, which include brackish hot spring seeps, allow and encourage the formation of this remarkable shape.
Cladophora balls are a mobile form of algae and exhibit a number of interesting "behaviors". These include rising and sinking in the water column in response to light, rolling about and dumping collecting sediment from their surface and rotating positions with other Marimo on different tiers of the lake bottom. This last phenomenon allows Marimo to be found at deeper depths than light would allow for stationary plants.
The Japanese have taken a great fondness towards this algae, declaring it a "Special Japanese Natural Treasure." They have built a Marimo Observation Center at Lake Akan, complete with 24-hour video surveillance of the Marimo at the lake bottom. The Marimo center is visited each year by over half a million Marimo loving thrill-seekers.
Hope this helps, Eddie
