To grow HC you need good CO2 more than anything else. A pH controller has nothing to do with that. You can't magically dial in the right amount of CO2. You have to start by making sure you have a good amount of dissolved oxygen in the water, by having the whole water surface rippled - no with splashing, but with ripples over the whole surface. You need to do something to get good water circulation throughout the whole tank, so CO2 can get to every plant. Then you need to know approximately where to start with the CO2 "bubble rate". I like using a drop checker for that, but many others don't do that. Eventually you want to increase the bubble rate slightly every couple of days or so, watching the plants to see if they show any better/faster growth, and watching the fish for distress. Once you find that increasing the bubble rate doesn't improve the plant growth rate, or cause more pearling, you can assume that you have enough, if not slightly too much bubble rate. Now, you just monitor the bubble rate every day, keep pruning so the plant mass doesn't quickly double, increasing the need for more CO2 or blocking the water circulation in the tank.