There is some research on these ecosystems [1], and there dynamics [2,3]. The ecosystem is made up of a photosynthetic algae as a producer, a protozoa as a consumer, and a bacteria as a decomposer, and can be stable for over 1,000 days.
Stable for 1000 days is not the same thing as 'will remain clean for 1000 days'. Have this phones a undisclosed problem with overheating that would suggest to add water as heat buffer?