After having the ultrasonic device a couple of weeks in operation it looks as if there more algae than before. What happened ?
Of course this is not the case, it only LOOKS that way! There are two reasons why it appears like that: a) sometimes (roaming) algae do not sink to the bottom after being killed, but form a tiny methane (gas) bubble, which makes them drift to the surface, giving the impression they have multiplied themselves. If one pushes the dead algae aside one can see the clear water underneath. After a rain the bubbles will have broken and the dead algae will sink to the bottom. If one has a problem waiting for this to happen, the algae should be scooped off. b) dead filamentous algae are loosened from bottom and sides and they fall apart, thus causing the volume to look bigger. Dead filamentous algae ALWAYS have to be taken out because they block the water surface and absorb the sound like a blanket.
