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Why do you need to soak them?
If you're trying to remove debris, algae, or stains, try running very hot tap water over them, or dipping them in near boiling water, and wiping them with a soft, lint-free cloth. Hot water will kill anything as well as bleach or peroxide. Remember though, that much of your beneficial bacteria will grow on decor.
I don't have the patience to scrub every single leaf on every single plant I have. I would rather just do it the fast way and soak them in peroxide or bleach