Yellow leaves

Need some info, like how often are you feeding, and at what strength and what nutrients? Also need to know what you are adjusting your pH to before you are watering into the medium. It's certainly is a issue to do with making the leaves green, which is generally nitrogen and magnesium. If it's started on the lower area of the plant then it's a mobile nutrient and both of those mentioned are mobile. If you have some epsom salt around the house, add a teaspoon to your next 1 liter / quart of water and dissolve that in and water then. If it's magnesium, they will begin to green up in a few days. Don't delay though because leaves can reach the point of no return and the leaf will die. If you aren't adjusting the pH of your water before you water your plants, you really need to find a means to do so. It's vitally important the pH is in the correct range for all macro and micro nutrients to be available to be absorbed. Anywhere between 6.0 and 6.8 and your plants will be able to eat sufficiently to maintain health and vitality.