For the better part of a year I had trouble growing chaeto. I would buy it, it would slowly die off while hoards of GHA invaded my display. I had a 10gallon separate refugium tank. The refugium would get overgrown with gunk and the chaeto would die. I think my flow was too low but what I finally realized is, we are conditioned to hate nuisance algaes and we want to get every scrap out of our system. Then I evenually realized, why fight it if GHA is what wants to consume the nutrients I have in my system why not use it. So I built an algae turf scrubber and it works amazingly well. And I built it over a 5 gallon tote in place of my 10g refugium, just so I could have a place to fill with rock rubble for pods that fall out of the scrubber. And amazingly, the scrubber grows pods like crazy. They love GHA just as much as chaeto if not more. My glass is covered in pods even during the day. Because of the super high flow and light only has to penetrate a thin screen of water, conditions are so good for algae in the scrubber that it cant help but outcompete your display. At least it worked wonders for me and I was in the same boat as you. Chaeto is picky and no one agrees on what conditions are best for it. With a scrubber there are detailed guidelines that pretty much guarantee success. Plus chaeto doesnt really consume phosphate which was the main reason I had GHA so bad. Anyway sorry for the long-winded post but that's my experience.
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