TetraPond AlgoRem, supplied by 123 Aquatics is Tetra   s answer to Green pond water. Green water is caused by the presence of millions of suspended algae cells, which multiply rapidly during the spring and summer.  Not only is green pond water unsightly, but it can also adversely affect the water quality in the pond. AlgoRem quickly removes these algae cells from the water column, allowing them to be sieved out by the filter, or removed manually. Where there is no filter the clumps will either float or sink allowing them to be removed with a net or a vacuum.