If I double the size of my screen (provide enough flow) and get the screen to mature would I be able to go twice as long between cleanings?
Time between cleanings is generally a function of how thick the growth gets and how much (and what type) of light you are providing it. So there isn't a simple answer to this question, it's one of those "it depends" questions. I think that in general, it will increase the time between cleanings, but it's not necessarily linear (double size does not equal double growth cycle time) If you are getting good thick green growth, but your lights are not very strong, the lower layers are going to lack light and you can get die-off no matter what size your screen is. If it's an open-air screen, that generally lessens the cycle time to die-off when compared to an enclosed "3D" growth box/chamber If you don't have the nutrients/bioload to support a screen that is 2x the size, then the growth type could change a bit, resulting in lighter or yellow growth, which can block light and inhibit GHA sometimes, so you might take a step backwards. But these are all just possibilities. More info on your specific setup would help narrow down the "what ifs" a bit...pics, background, tank/system info, etc...