what is the little square for on the oceanmagik live phytoplankton container?

[leonardomanzano]

OceanMagik

OceanMagik is a nutritious mixture of four Live Phytoplankton strains (Nano, Iso, Tet, and Thal) that is great for feeding copepods, corals, clams, and other filter-feeding inverts. OceanMagik is a hand-selected blend of the most nutritious Live Phytoplankton strains available.

www.algaebarn.com

Here's an image of the bottle.
is it fertilizer? if so is it the F2 formula or something else?

I started my culture with a new batch of saltwater assuming it's not fertilizer how long do I have before the culture starts to die?

also, I am not entirely sure but will too strong of a light source kill my culture? Im not seeing too much on the web. But I have experience will hurting some of my pepper plants will lighting that was too strong/hot. Is this something I should be worried about with my phyto?

im using some generic light i bought on amazon

 

[TheyGaveItToMe]

If you are talking about the little container on the top right? It is for measuring out the amount you want to dose to your tank.