ABSTRACT
Microalgae are protists with eukaryotic cell structures which can be found in aquatic ecosystems such as rivers, lakes, reservoirs, ponds, and oceans. The protist culture method can be considered as a technique to allow protists to grow in a certain controlled environment. The objective of this study was to determine the growth of microalgae in the different water sources A modified closed photo-bioreactor (bottle) was used in this research. The number of experiments was 130, each experiment comparing 5 different natural water resources which are well, pond, pool, paddle, river, tap water, and mineral water and tap water as control, all with 25 replications. Those bottles were put under the sun for 2 weeks. Every day, the colour changes were documented. The result showed that within 2 weeks, no colour changes for mineral and tap waters. On the fourth and fifth days, the watercolour of rivers, ponds, paddle, pools turn the greenish or murky brownish. This indicated the growth of microalgae in the bottle. The different colour indicates the different species or a group of species. This simple experiment able to be developed for practical work during pandemic Covid-19, when students have to study at home, but are still able to get their competence by small project-based learning. © The Authors, published by EDP Sciences.