Prof. Boyd provides additional insights into fertilization of aquaculture ponds, discussing phytoplankton requirements, organic and inorganic fertilizers, and other relevant aspects of pond management.
Light penetrating water is scattered and absorbed exponentially as it passes downward. The presence of dissolved organic matter and suspended solids further impedes light penetration, and different types of solids absorb different wavelengths.
The simplest tool for assessing phytoplankton abundance in aquaculture ponds is the Secchi disk. An electronic turbidimeter can be used to measure the amount of light scattered by a water sample.
Trials with recirculating shrimp nursery systems in India supported the use of biofloc. To control ammonia is a way to reduce filtration costs.
It would be difficult to find a pond aquaculture worker who has not measured Secchi disk visibility or at least seen someone measure it.