Pife, I don't know anything about gluconate.
I know Seachem uses it in their liquid sr. And ca. Supplements.
It's probably just fine to use but I have heard that it can throw a calcium test off because the test kits can't read calcium glukonate properly..
Reall not sure if the same is true of sr. Gluconate.
Any thoughts or insight? Like I said, I'm just curious as I don't know anything about it. They've been using it long enough that if it were bad, they wouldn't be using it anymore..
Just looked up gluconate and it is an organic carbon.. wonder it it will feed denitrifying bacteria..