I have made many references to this particular version within discussions of my perceived faults of the UAS design as one possible actual good design, mainly with respect to water flow across the screen. I searched for hours and could not find it, then I found it today so I wanted to get it set in stone here for future reference. I have contacted the user "Expressions-LTD" to see if he has any updates. Maybe he will post it here. Thread: http://algaescrubber.net/forums/showthread.php?2461-Scrubbers-that-did-NOT-work-thread First crack: Modification (Fail): "Current" modification (waving flag)
Could be too few bubbles, and that the increased flow just made the contact time of the few bubbles even less, and made the second version non-functional...(?)
I think it somehow changes the flow pattern in the unit, therefore exposing the algal strands to pulsed light.
Why should pulsed light be of any help? The sun isn't pulsed is it? So why should algae prefer pulsed light?
In theory, the waving (if this screen achieves this) provides light deep down into the growth in an intermittent fashion which reduces self shading (increases growth) as well as proper nutrient circulation (increases nutrient uptake [gonna start a thread on this soon]).
"pulsed light" is what is more commonly referred to as "flashing" and yes that does make a difference, but we most likely already do it. Just like the light patterns on a pool bottom on a sunny day, waves focus sunlight into very intense lines on the reef floor in the ocean, and this has been studied (for upwards of 100 years). Studies show that if you flash algae instead of having constant light, you get the same net effect on growth. Some studies suggest that you get this with a dark period as much as 10 times longer than the light period. But between a falling sheet of water or an upwards rising wall of bubbles, we very likely are incorporating this flashing action without being aware of it. Such flashing, if one were to be able to utilize it, would likely only reduce power usage. I have to wonder if it would affect adhesion, because when I went to 30 min on / 30 min off continuously, my growth was not well adhered to the screen, in fact I had significant detachment for the first time ever. One possible conclusion was that the long light period allowed light to penetrate deep enough to keep photosynthetic activity sustained at the base layer, and the short photoperiod was not penetrating deep enough to sustain that process for a long enough period of time, and the roots died. But back to this particular scrubber concept, the flag, I thought that this was one possible method that solved the flow issue that is inherent to UAS devices. But, I haven't received any response from the guy who made it.
