I'm sure I have a lot of misconceptions. lol. One of them is probably that I think it's possible to get my plants growing faster than my goldfish will uproot them. As for nitrate, I'm consistently testing at zero in a overstocked tank, although I'm sure it's not really zero. I do 10-12 percent water changes weekly, but nitrates aren't elevated before the change. As for lights, my red ludwigia turned red again when I replaced the fluorescent with LED. I'm sure most people here have a better light setup than I do, but to me if red ludwigia is red, it's not truly low light. Maybe dirt with goldfish is wrong for multiple reasons. I know there are people who say they have used a nutritive substrate, not sure it was literally dirt, with goldfish and a good cap of pebbles or small rock. Right now, I have a precariously balanced tank. The plants are surviving, but not thriving. That's what I'm trying to get a handle on before setting up the new tank. I'll research fertilizers. But I can't see myself adding nitrogen to the tank, unless there's a way to get it to the roots and not the water column. Thanks for the feedback. I realize most plant guys aren't goldfish guys and vice versa. But I'm on a mission. I will have a heavily planted tank with some big, fat, happy goofy-a gold fish.