I’ve had the best luck with Seachem Prime — it’s been super reliable for my arowana setup. Does the job without clouding the water or messing with parameters, even during big water changes.
I tried a cheaper brand once (don’t even remember the name) and noticed my arowana acting weird for a day or two after. Never again. With sensitive fish like arowana, I’d rather pay a little more for peace of mind.
Curious what others are using too — always good to compare notes!