The photoperiod (for a mature screen) should be based on the NO3 level you want to target. A longer photoperiod = more inorganic nutrient assimilation, & vice versa. The photoperiod to achieve this is dependant on the screen size, the watts of light, & the spectrum provided, & the amount of food added per day.Actually, I've boosted the light duration for this new unit to try to get it 'up to speed' more quickly. Normally, I run 14 hours ON and 10 OFF. Always figured it was important to give the turf algae a 'break' …. like in nature.
A minimum photoperiod of about 9 hours per day has been recommended. Ive tried 24/7 illumintion & there was no negative effect on the algae. In fact the algae grew much faster, but NO3 bottomed out to zero.
Based on the available recommendations I aim for 1W to 1.54Watts per 4 square inches of screen, per side. That's for red 660nm LEDs - 2.2V @ 700mA = 1.54W. I imagine that the higher figure is nearing photosaturation.I'm also using much more powerful lights that I have in the past; even accounting for the larger surface area.
You've got a bit above 22 gph per inch of screen width. 35 gph has been recommended, but once the flowrate is fast enough to fully cover a mature screen without channelling (on a downflow scrubber) it is debatable wether increasing the flowrate any further increases efficiency, & too much flow has been reported to be detrimental.Approximately 20 linear inches of screen width getting a total of 450 GPH (maybe a tad low) a