Aquarists often read about lowering the temperature in the aquarium at night, as this happens in the wild and is said to have a positive effect on the plants.
The JBL expedition to Colombia decided to get to the bottom of this: In a blackwater stream on the border with Venezuela, the JBL research team attached a waterproof temperature logger (ELV WTDL1-2) to a root in the shaded bank area at a water depth of around 40 cm.
The drop during the night was 1.5 °C, but only in the lagoon. There were no lower water temperatures measured at night in the main rivers.
As many aquatic plant species tend to prefer cooler water temperatures, any improvement in aquatic plant growth is most likely due to the lower temperature, as with a night-time drop. Medium and large bodies of water, however. show no changes in water temperature between day and night. Only in the rainy season does the water temperature drop slightly due to the reduced solar radiation.
