I'd like to try and put some of my aquarium plants in pots so that they can be moved around more easily, especially if I decide to convert one of my tanks to brackish. The best guide I could find was this: https://www.gardenguides.com/101705-plant-aquarium-plants-pots.html
But all it says about what soil to use is "carefully choose which soil to use." Lol My question is whether I should stay away from potting soil mixes. I have an old planter with some potting mix that has been "used up" by plants for one season- I grew Swiss chard, for example. I would expect that I could safely use this soil to pot the dwarf tiger lotus I have, which- ideally- would grow happily in my outdoor mini pond. I am planning to cap the soil in the pot with gravel. Anyone see any red flags with this plan? I don't think the soil would leach any harmful chemicals, but I am going to review Diana Walstad's book to confirm.
Edit: Got Walstad's name wrong!