Pond Boss Forums INTRO Questions & Observations Red Pond Dye, Red Tide, or What?

Theo - After stratification the dead productivity and organics that develop in the upper warmer water will settle to accumulate above the thermocline. Decomp of these materials releases dissolved organics. The rain event did mix the upper layer/s of the pond. These dissolved organic chemicals and types of nutrient enrichment are favored by at least one to several types of Euglena that often has various hues of red. This algae group is usually an indication of excessive amounts of dissolved organics in the water due to various reasons. From link below. ""As reliable indicators of organic contamination, the euglenophytes are investigated primarily for their ecological significance as phytoplankton."" The redness can even change during the day to green based on amount of sunlight and the type of food consumed by these algae. This interesting algae has been reported to sometimes produce toxins from my limited bank of knowledge for this 'critter'. When the dissolved organics get depleated the dominant red form of Euglena dies out. FYI this algal group of Euglena is a lot different type of algae than the algae that causes "red tide".

Advanced reading with some pictures of red water conditions. Later in the article it shows the water color change that can happen during the day.
https://pmc.ncbi.nlm.nih.gov/articles/PMC11063437/