According to the Biotherm Asian website* it contains 5% of L'Oreal's patented plankton exact: Vitreoscilla Ferment (in water). This plankton rich water is produced by a patented process by L'Oreal in laboratories since 1994. (Before it was harvested from a lake in the French Pyrenees.)
According to the website, this product contains the highest concentration of the fermented plankton of all products (along with the Life Plankton Essence and Life Plankton Emulsion). (Other lines that you can find Vitreoscilla Ferment is the entire Biotherm line and other L'Oreal owned brands such as Lancôme and Vichy.)
The product basically is a thickened water-alcohol mixture - also called Gel Cream. This is basically a gel cream and nothing special about it that would limit its use to "a few nights a week". (A product like this might be welcome in a humid climate and/or by skin that tends to be oily and acne-prone due to its very light feel and clean feel on the skin after application.) One should also keep in mind that the product was originally developed for the Asian market and for Asian skin types that tend to be oilier and more resilient and the climate is hotter and more humid than a regular European continental or the North American climate.
It has a very light and somewhat cooling feel on application that will quickly settle into a semi-matte finish that looks like skin just with an even more even and perfect finish. I feel it is adequately hydrating now in the warmer summer months.
I also do like the Life Plankton Essence and now using the fifth bottle.
Ingredients : Aqua/Water, Glycerin, Alcohol Denat., Dimethicone, Butylene Glycol, Tin Oxide, Carbomer, Dimethiconol, Sodium Hydroxide, Adenosine, Disodium EDTA, Caprylyl Glycol, Vitreocilla Ferment, Phenoxyethanol, CI 77891 / Titanium Dioxide, Mica, Linalool Geraniol Limonene, Citronella, Benzyl Alcohol, Benzyl Benzoate, Benzyl Salicylate, Parfum/fragrance (F.I.L. B178835/1)
5% Life Plankton