Thank you

I did a calculation and it said I would need 60lbs of Flourite to achieve a 3" deep bed, I did it for Eco-Complete and it came up with 90lbs. Why would I need so much less Flourite than Eco?
I was planning on dosing some light dosing of liquid Flourish as well

Is there a floating plant that has roots that hang down into the water column thats compatible with my low lighting? Ive never had much luck with hornwort in the past and am a bit aprehensive about trying it again.