Okay, so there are two choices, then.
If I add flourite, how much can I add at a time without stressing the plants too much? 1/4" per week? maybe? I like the flourite for the red colour; I've used it and it does cloud the water (even rinsed well), it's a pain. Eco Complete is black, right? I'm looking for something that looks natural to me, so the closer to sand colour, the more I like it.
Choice two: put fish in a bucket.
My concern with this is 'will the tank have to cycle all over again'?
For either choice, I'd be using the current gravel, plus the flourite (or whatever else I might decide on). Would I rinse the current gravel clean, or would I leave it somewhat dirty with the mulm that has collected deep down?
PS. I updated my sig to current situation. The rosy barbs started snacking on my plants, so they went to the flea market to find new homes (happy ending)
Thanks for all your care, Ingrid