I am struggling to control the Nitrate level in my planted tank. I have 25 small fish in the tank mainly Barbs, Tetras and a few Otoâ€™s and am aiming to keep the Nitrate level at around 50 or below if possible however I have never managed to achieve this since starting up the tank about 5 months ago. I use a Nutrafin Nitrate test kit (liquid type) to test the level but it always reads at the maximum colour shade which equates to 110 so it could be even higher than this! All my other water readings ph, phosphate, ammonia, nitrite etc are good and I use Co2 injection for the plants and the drop checker is a permanent lime green so I think all is ok there. I change 50% of my tank water every week and vacuum debris from the gravel at the same time. My replacement water is Nitrate free. My fert dosing regime is: Aqua Essentials Trace Mix Plus 15ml x 3 times per week James Planted Tank Macro Solution (Potassium Nitrate / Potassium Phosphate mix) 35ml x 3 times per week Iron Sulphate 35ml x once per week The plants all appear to be growing well the only notable issue is that a number of the Echinodorus Bleheri leaves have black edges and the veins are quite pronounced. My main concern in all of this are the fish which do seem nice and healthy even with the high Nitrate. I had hoped that the plants would use the Nitrate and keep the level low but this does not appear to be happening. Could it be that the Potassium Nitrate is helping to keep the Nitrate level high? As always all advice is much appreciated.