I honestly have no clue. As I said, it probably doesn't have much value. But I *hope* that it will allow me to suppliment a tiny bit of extra ferts over a long period. I like to think it eases stress on my invertabrates. Yes, I realize it has no real value for ECA, but it might be neat for something like Green Bacter.
I think it works along the same principles as this (ADA Green Drop):
One end of the glass is inserted into the fertilizer bottle, while the other end is placed in the water/substrate/filter intake.
But I have yet to find "Slow Drop"s niche

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