Hi again. Below is my "quick and ugly" setup of peristaltic pump for dosing micro/macro (setup is only for testing but as you know temporary solutions sometimes stays forever ). Peristaltic pump is from ebay ~Â£19 incl. postage, rest of that stuff was more less free (12V PWS found at work, some tubes), also I had to reconnect one light tube to another timer socket. I measured flow rate and its ~ 5ml/minute so its quite convenient for calculations. Outlet I stick together with filter outlet tube over the water surface. Because the gearbox (ratio 1:150) between engine and pump itself its quite noisy I have to think about some enclosure in the future.