Planted tank needs more, not less water movement for gas exchange and to evenly distribute nutrients and CO2, but not strong current to uproot plants, particularly carpet plants during establishment stage. Humus rich substrate can provide nutrients to rooted plants for some time, until eventually runs out of nutrients and need to be replaced or replenish of nutrients from the water column. Moreover, potassium and iron are absorbed through water column mainly as not much is biologically available in the substrate.My tank is quite heavily planted and i find myself wanting more and more water movement. The op has substrate plants that wont be harmed by the flow as they feed from the substrate. Worrying about co2 levels is only something that needs to be done if you are dosing it. Low tech planted you just want surface movement for oxygenation.View attachment 1377419
The Columbia tetra look good in big group. Do they still school or males spend time fighting one another?