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walstad tanks

1133 Views 2 Replies 3 Participants Last post by  Diana
Is using an air-driven sponge filter bad for a Walstad tank? I'm inclined to think so, since the surface agitation would cause co2 to gas out. But at the same time, there should be some surface movement to prevent any biolfilm.
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Unless you're injecting CO2 via a pressurized system (which isn't really a Walstad tank), it isn't a big deal...
A gentle ripple at the surface, from any source is about right. Enough gas exchange and water movement throughout the tank, but not too much.
I find sponge filter run by bubblers do not create much water movement deep in the tank, but create a lot of action at the surface. I would rather do the opposite. I mostly run Koralia power heads, fairly low in the tank, but aimed slightly up. This will create more water movement lower in the tank with just the amount of ripple at the surface that keeps the scum broken up.
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