The discussion was here and you chose the wrong reference to defend your position...
1.) Horizontal ground PBR's have 100 % exposure to light therefore the algae strain growth and/or duplication is many times quicker than a vertical due to the fact that the lower tubes are shaded from the upper tubes of the vertical unit. You get even light exposure across every tube at the same time.
If there was such a thing as 200% wrong, this would be it. First of all, nobody is hanging "tubes", most are using a thin bladder of some type. Second, the ONLY time you get even light exposure on BEHL's system is at high noon. Third, Laying on the ground side by side means that you need to wait till the sun is higher in the air before you get your first exposure to the sun, and higher still before it can reach all tubes, or all of the tubes depending on the alignment to the sun. Tubes that get exposure early in the morning will get less in the evening and the tubes exposed to the sun later in the day will get more later. The Algae will be exposed to changing conditions all the time as they get pushed around by the pig and the potential for uneven exposure is greater in the flat systems. Ever seen vertical blinds? Take a good look at a set and consider if they were hanging bladders of algae and how by standing up they are exposed to even the earliest and the latest rays of sunlight throughout a day. Take into account how only their edges overlap and how nearly the entire bladder is exposed when angled ever so slightly towards the sun.
2.) Horizontal PBR's require the lowest amount of pump pressurization GPM (gallons per minute) to push the liquid through the tubes. There is little friction when pushing the viscous liquid across the tubes on a flat surface. Also, the flow is a constant pressure providing stable consistent growth. The vertical would require alot of pressure to send the liquid back to the top then a systemic valve set up to reduce the flow when going back down.
Once again this is pretty much completely wrong. Water need only be pumped to a reservoir to supply a gravity feed system and rather than pressure controls you need only limit the size of the flow lines because they will only carry just so much water at one time. If the system was set up with a catch reservoir(and likely would be) then you could use a 1:10 ratio for pumping meaning that for every 1 minute you pump the water up, it takes 10 minutes for gravity to bring it back. A simple float switch would trigger the pump same as your toilet does when it's low on water. Most of this stuff could be found in your average Home Depot at very low cost anyway.
3.) Horizontal PBR's can be accessed without ladders or scaffold. The labor cost to manage a horizontal unit is much less and much safer. Everything can be constructed safely on the ground by ONE person if need be--without the use of expensive equipment to reach higher tubes. Plus tubes that are higher must have supports or they will bend, kink up and possibly come apart
Once again, NOBODY is hanging tubes. And consider the difficulty of hosing away the water and algae from a busted vertical bladder and moving on versus having to break down the ENTIRE system and cleanup the entire mess left from BEHL's setup. In a vertical system you lose one bladder and until the flow is shut off, you will lose what was pumping into that bladder. In BEHL's system, one busted tube would evacuate the entire system in just a few seconds and you would be left with one hell of a mess to clean up. BEHL is catching their leaks in a sandbag and plastic pool. Vertical systems do not necessarily need ladders or scaffold to access either. Most of your entire argument is based on the assumption that someone will take the most expensive, most dangerous, and least efficient route when constructing their system. If ONE person was doing vertical you could argue they were crazy, but when MANY people go vertical, you usually say "They're on to something".
