US application 20150225684 titled PHOTOBIOREACTOR
From the specification of published US application 20150225684 to Spicer Consulting Ltd :
 Commonly, open systems are used for growing and harvesting algae on a mass scale and allow the algae to be `open` to `the elements`, namely exposed to outside (external) conditions. Closed systems are also commonly used to grow algae; these systems often require expensive equipment and have long start-up times before an increase in algae biomass can be noted. However, both open and closed culture systems have limitations as neither are able to fully exploit ideal environmental factors which optimize a growth of a given algae; optimal environmental factors concern, for example, light and temperature conditions, for example which mimic a particular climate zone in which the algae is a natural inhabitant.
 Therefore, there arises a need for a system for determining optimal growth parameters for various species of algae. In particular, there arises a need for a system that provides a basis for temperature, lighting and mixing regimen on a larger scale, whereby a given user/producer would expect to achieve a best performance with regard to biomass yield and/or quality. Furthermore, it would be desirable for the system to allow predictions to be made to determine a relative impact of seasonal or geographic differences in light intensity, photoperiod length and temperature cycles. This is important information to inform producers of various key factors that will influence yield and so forth. Moreover, this would allow implementation of control measures to lessen an relative impact of non-ideal growth conditions and to improve an overall yield.
 Therefore, there is a need for an improved apparatus and system for informing users of the optimal growth parameters for various species of algae and optionally other types of organisms and/or microorganisms.
First published claim:
A method for non-invasive growth measurement of organisms in an apparatus for growing and harvesting organisms or substances derived from such organisms, wherein the organisms are in an aqueous medium and are housed in a culture vessel, the method comprising: providing means for measuring an opacity of the aqueous medium for estimating a growth rate of the organisms; wherein the means for measuring the opacity are arranged in the apparatus such that they are located at one or more predetermined locations relative to the vessel; wherein the means for measuring the opacity are calibrated to account for refraction, absorbance and reflection caused by the vessel at the predetermined location; and measuring the opacity of the aqueous medium at the predetermined location.
Separately, note US 20150225689.