Outbreak of cyanobacteria can cause problems with water quality in summer months. Cyanobacteria is a bacterium that produces poison called cyanotoxin. When the concentration of cyanobacteria increases, the phenomenon „algal bloom“ appears, which is very toxic and may kill all the organisms. The ecological reduction of growth of cyanobacteria is carried out by aeration of water. The mechanic and pneumatic aerators are very often used but these equipments are not cost-effective and have a high consumption of electricity. This article is focused on potential more cost-effective aeration via hollow fibre membrane. This technology is bubbleless and almost all oxygen delivered is dissolved on the membrane. First part of the article is focused on measurement in the laboratory and testing of modules with hollow fibre. Second part is focused on the distribution of disolved oxygen in the whole reservoir with small depths which is ensured by a small partly autonomous boat.