The new jetwashed Purbeck stone I added to the tank a couple of weeks ago has, in places, developed a nice growth of green algaes, grazing by snails keeps down hair algae and entero-type growth whilst some broader leaved sprouts have appeared as well as a few branching red algal growths. Its hoped that coralline algaes will eventually predominate.
To allow the maximum potential for new organisms to colonise the tank its necessary to carry out water changes, adding fresh seawater at fortnightly intervals increases the chance of catching planktonic spores and larvaes during their often brief time as plankton. Various animals and plants release spore and larvae at different times of the year.
Obviously using a plankton net with an aerated collection bucket allows far more plankton to be captured and introduced to the aquarium. A few problems have to be overcome to achieve this: open water is better, a boat is useful. A power supply to keep an air pump going - a car battery starter with a 3 pin socket outlet is enough to power a pump for 2 or 3 hours and if possible a cool box to transport the plankton on any car journey, die-off is rapid at elevated temperatures.
I keep an aerated bucket of phytoplankton to allow regular feeding of the mussels and cockles, although the aquarium has a healthy plankton population anyway, I am of the opinion that its a good idea to keep the aquarium seeded with new infusions.
The skimmer will remove a certain amount of plankton, this is inevitable and perhaps the only downside of skimming a natural aquarium. However, the benefits of skimming, in my opinion, far outweigh this drawback.
It is possible to entirely populate an aquarium using only seawater. Algaes and crutaceans, sponges and soft corals are propogated via planktonic cycles in their lives. Mussels in particular are early colonisers of new habitats, during WW2 dykes in Holland were damaged by Axis bombing flooding certain areas. When the dykes were repaired after the war and the land was pumped dry again mussels were found hanging from previously submerged tree branches and the eaves of houses! Under the right conditions this can be replicated in a captive enviroment. A refugium, with only a few rocks and some sand or gravel, will, over time develope a population of plants and animals entirely from the addition of fresh seawater. Its an interesting diversion and worthy of study as a seperate entity from the main display tank.