algae turf scrubber

multicincta

New member
I'm going to build myself a scrubber, but I'm wondering why every feels the need to run water over the algae? Why not simply have your screen in a narrow "wall" of acrylic and have your water be bumped through this containment area, filled to the top of the screen. Water will still be circulated through this system and thus having nutrient exchange. Is a system where the water pours over and runs down the screen/algae better for some reason?
 

multicincta

New member
It is not about feeling need. It (the turf algae) needs to be exposed to air....

The algae does great living in my tank, LOL. What benefit is there having it exposed to air? Does this allow it to better use the unwanted nutrients in the tank? I'm sure it is using up those nutrients by developing on my rock which is completely submerged in the DT.

Basically, I'm trying to understand why it is better to have the water running down the screen rather than simply being submerged. I'm fine going either way, I just don't understand why one way is better than another. If algae needs contact to both air and water, ok, but what makes this better than submerged?
 

chuggy

New member
you want the lights as close to the screen as possible. how you gonna do that underwater? The more light on the screen the better it works.
 

realtime3d

New member
you want the lights as close to the screen as possible. how you gonna do that underwater? The more light on the screen the better it works.
You can sufficiently light a screen while submerged.

It's been about 15yrs since I read Adey's book but I seem to recall the main reason for a non-submerged screen is for efficient gas exchange. I'd imagine it's pretty easy to get CO2 limited with significant algae production.

Algae will grow where it's needs are met. Different types of algae grow with different conditions -- more/less flow, diff light spectrums and intensity, nutrients, etc. Most of the guidelines for algae scrubbers have evolved over the past 15-20 years. The guidelines help make the right type grow where you want -- on the screen versus in the tank.
 

multicincta

New member
you want the lights as close to the screen as possible. how you gonna do that underwater? The more light on the screen the better it works.

Easy, build a narrow acrylic container just like most people already do for their scrubbers. Allow the water to flow from the top and exit the bottom to a stand up pipe that dictates the level of the water within the acrylic container. Place the screen inside the container and the lights on the outside right up to the acrylic just like the rest of the scrubbers do. Thank of it as a narrow tank.
 

dogstar74

Premium Member
The biggest problem that I have with that idea, is that the coraline, and algae will grow on the acrylic surface closest to the light rather than on the screen, thus it would cut down on the effectiveness of the screen at an almost exponential rate. But I suppose it could work.
 

widmer

Drug Enthusiast
1. Even though it's called an algae turf scrubber, no one these days actually uses turf algae anymore. They just allow microalgae to colonize the screen. Most commonly people seem to end up with green hair algae which is wonderfully prolific.

2. People use vertical external screens for two reasons: 1) The thin sheet of water that forms allows for very rapid, turbulent flow which is best for encouraging algae growth and 2) gas exchange. The first reason is the most commonly described though.

You simply won't get that rapid turbulent flow if the whole thing is submerged, even if you think you are blowing current by it, it likely won't suffice.
 

BeanAnimal

Premium Member
The algae does great living in my tank, LOL. What benefit is there having it exposed to air? Does this allow it to better use the unwanted nutrients in the tank? I'm sure it is using up those nutrients by developing on my rock which is completely submerged in the DT.

Basically, I'm trying to understand why it is better to have the water running down the screen rather than simply being submerged. I'm fine going either way, I just don't understand why one way is better than another. If algae needs contact to both air and water, ok, but what makes this better than submerged?

"One way is better than the other" based on the type of algae you intend to grow.

The species that grow on the screen grow faster in an air/water environment and will provide faster export than the species that grow under water. Your "acrylic box" will not provide the air contact and (as mentioned) will quickly become fouled, blocking much of the light.
 

kcress

New member
Actually the new twist on ATSs is the FATS. Or Flooded ATS. It indeed is exactly a fully flooded screen. So yes it will work. In fact it works better than just the ATS. You certainly do need to keep the window clean! But that isn't a big problem since you have to clean the screens every week anyway.
 

pskelton

New member
I have been building a ATS and should have it up this weekend. While building it I decided to do an experiment. I have a Maxi-jet sure flow pump on the back wall of my tank. I noticed that I had GHA growing on the rocks directly in the flow of the pump and it was growing on the shroud. I wanted to see if I could purposely grow GHA on a screen attached to the pump so I took a roughed up piece of plastic canvas and wrapped it around the end of the pump shroud. The piece I used was only big enough to wrap half way round the pump and it extend out about 10 inched. I placed it so it was curved upward so that the "U" shape was facing up towards the lights. I have ran it for about 6 weeks and I have not gotten any GHA to grow on it. I get a thick layer of diatom algae but no GHA.
 

multicincta

New member
See, Kcress is with me on this. Sounds like I simply have to keep the acrylic clean and I'm good to go.

Thanks for the input gang, this is exactly the type of discussion I was looking for.

pskelton, what is GHA?
 
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