My tank water parameters are as follows:- PH 8.2 Ammonia 0 ppm Nitrite 0 ppm Nitrate 10-20 ppm KH 12Â° dKH 215 ppm GH 17Â° dGH 304 ppm My tap water (water tested straight from tap) parameters are as follows:- PH 7.2 Ammonia 0 ppm Nitrite 0 ppm Nitrate 10-20 ppm KH 14Â° dKH 250 ppm GH 19Â° dGH 340 ppm I am planning to keep Rainbows, Amano Shrimps, Gouramis, Angel Fish, and Cardinal Tetras. I will also be planting many plants that mostly prefer softer water. I will be adding CO2 and dosing with dry fertilisers (EI Method). I would like to reduce the hardness of my water if possible, I was planning to use half tap water and half RO Water. I would ideally look to achieve a GH of around 10 dGH for the plants and fish. If I am using CO2 and dry fertilizers is there anything I should be aware of about doing this. Will the CO2 reduce the hardness?