Supa Anti-Algae Pond Block is a slow releasing Algae preventative.
When placed in the pond, the block slowly dissolves releasing di-methyl urea into the pond waters as it does so. This is totally safe for fish and stops the growth of water born algae.
Whilst totally harmless to fish and healthy pond plants this inhibits the growth of water born algae.
Prevention is always better than cure so the introduction of this item in early Spring will prevent build up of algae as the weather warms.