I have just bought some new gravel to replace the rather course 'cotswold stone' type that I currently have. I have bought a finer gravel for my loaches, but I have also realised that my current gravel is keeping the water hard, despite my efforts to reduce the PH and hardness ( the gravel has either lime or carbonate in it). I was undecided about whether to change it in one go or remove half of it because of cycling. My new filter is cycling well now and I have zero Nitrite. I have currently taken out half of the gravel and put this to one end of the tank, putting new gravel at the other end. I really wanted to remove it all so that I can get my GH and KH and acidity down. If I do this, and provided I keep an eye on the nitrite and do water changes if necessary, would this be acceptable
