Hydrometers for Algae Cultivation

Hydrometers are small glass or plastic tubes equipped with scales used for measuring specific gravity. One end features a bulb-shaped design, housing steel or fin lead shot as a ballast that keeps the hydrometer upright in sample liquids; when aligned correctly on its scales, specific gravity readings appear. Different varieties of hydrometers can be found used across industries like distillation or water testing, although distillation operations often employ them.

Monitoring environmental parameters like pH or DO in an ongoing system for cultivating microalgae is vitally important to ensuring high quality algae is produced, especially as microalgae can absorb nutrition from culture solution over time. Therefore, knowing when fresh seawater needs to be added as supplementation is of utmost importance for maintaining quality algae production.

At this point, we designed an inexpensive and user-friendly monitoring equipment for measuring pH and DO in culture solutions. The proposed device comprises of a dark box containing sample container 1 as well as an inexpensive Raspberry Pi camera capable of taking photos at predefined sampling frequencies. Pump 3 pumps water directly into this vessel from its connected culture tank via Valve 4, while valve 4 connects directly with freshwater supply line as it discharges it via Valve 5. While at the same time the solution within this sample container is continuously monitored using both pH sensor as well as DO sensor installed within.