Hi Tabwyo
I guess if you have been reading all the information on this forum you would have read and seen my posts regarding the horizontal approach to scrubbing?
I, like Routestomarket and others have had none of the problems that are said to afflict horizontal's. Like you say, and as I am finding, it is far easier to maintain, far less bulky, limited for space or not. I guess that's another factor as to why industry chose to go horizontal?
As Kcress said you want to use the 2700k bulbs as they give a good amount of the red light spectrum which the algae need. My scrubber has only been running since Wednesday and already my screens have a medium/light covering of brownish algae. I have the lights about 4 to 5 inches away and am using 3 x 18w CFT's (100w equiv) so a total wattage of 300w over an area of aprrox 20 x 10 inches. I'm getting a good spreade of light because I am using a lightbox that I made from white opaque acylic so it acts to spread and reflect the light at the same time. Even lighting I think is key and not all focused in one spot which seems to a problem for verticle designs. Much easier to light a horizontal ATS and keep the light contained.
My scrubber has an angle of just 15 degrees. The flow is fantastic with a pump rated at 1700 litres per hour but this I guess depends upon actual design? As Kcress said also you want to make the side walls of the trough at least an inch high, obviously to keep the water where it should be but when the algae grows up from your scree it will take the water level up with it. What I am personally finding is that as the algae is growing, the water now travels under the screen as well as over the top of it, so is effectively being fed from both sides. I guess this is because the algae adds some buoyancy to the screen ie trapped oxygen? It's working fine though, far better than some would have me or others believe it would.
Good luck and keep us posted.
UK and 'some' US scrubbers do it horizontally :lol: