This is a fast-acting treatment for blue-green algae or 'slime algae' (which is actually cyanobacteria rather than algae). Slime algae is the alien-looking dark green algae stuff that grows across gravel and spreads like custard skin. It tends to be caused by not enough filter bacteria (e.g. cleaning your sponges in tap water) or there if there is too much sludge in the gravel.
Should you do more cleaning?
Nope! By all means do your monthy gravel cleaning and water change as normal, but don't do anything drastic like a 100% water change as you'll upset your water chemistry and biological balance. Before using the treatment you should do a 30% water change.
To avoid an outbreak of slime algae in the future, remember to keep on top of your maintenance and try not to over-feed your fish. Make sure your plants are getting regular fertiliser and CO2 so they are growing vigorously - this means they use up all the excess nutrients in the water and out-compete the algae.
Dose: For best results, 10ml per 100 litres once a week for four weeks.
250ml treats 2500 litres
500ml treats 5,000 litres
1 litre treats 10,000 litres