What has happened?
Microscopically small algae, also called "Killer algae", (correct = algae bloom) reproduce in rising temperatures (above 15°C) explosively and colour the water green.

What can happen?
Underwater plants die due to lack of light. Fish suffocate due to lack of oxygen (Although algae produce superfluous amounts of oxygen during the day, they use this up during the night).

What has to be done?
1. The carbonic hardness must be tested (included in the OASE aqua activ "Test Set"). Is this below 5° dKH, lime must be added to the water with the "Hardness Plus" from the OASE pond treatment range aqua activ.
2. Test the pH-value. If the pH-value lies above 8.6 or below 7.5 also add "Hardness Plus".
3. Only after step 1 and 2 have been completed add Crystal Clear Instant Clarifier according to the instructions. The pond will recover in the space of 6 hours. Unpleasant odours will disappear. Plants can breathe again.

Will the pond stay clear?
Only if something gets done about the cause of the algae bloom. For example fish might need less food, dead leaves in Spring and Autumn should be removed, silt can be fought with micro-organisms (OASE aqua activ Sludge Minus), real underwater plants as well as floating plants should be planted in the pond.

Tip:
If you want to check the effect of Crystal Clear, simply take a jar full of green pond water, add 1 to 2 drops of Instant Clarifier and watch the water become clear after just 1 minute. Of course, this only works if the water contains enough carbonic hardness (OASE aqua activ Hardness Plus).