Even for a planted tank, 30ppm of nitrate is a little high. The plants should sucking it up more.
My thought is not enough co2. 8 ppm is low. Most people run at least 15 ppm of co2, while the majority push even higher up to 30 ppm.
You have enough light and if 30 ppm of nitrate is correct, you have plenty of nitrates. Add more co2, get the levels up, and in the process of doing that, think about adding fertilizers: nitrate, potassium, phosphate. You can use Seachem's lineup of NPK fertilizers, or you can look into dosing dry ferts.
Check out www.rexgrigg.com
My thought is not enough co2. 8 ppm is low. Most people run at least 15 ppm of co2, while the majority push even higher up to 30 ppm.
You have enough light and if 30 ppm of nitrate is correct, you have plenty of nitrates. Add more co2, get the levels up, and in the process of doing that, think about adding fertilizers: nitrate, potassium, phosphate. You can use Seachem's lineup of NPK fertilizers, or you can look into dosing dry ferts.
Check out www.rexgrigg.com