I have read enormous amounts of info on this topic and still struggle with my 120 reef. I have been trying to dial in my calcium reactor for over almost two months now. My CA holds at 420. I have a Ph probe monitor that turns my CO2 bubbles on when the PH in the calcium reactor goes above 6.8. The PH in my tank is holding at 8.1 - 8.2. My alkalinity is always spiking. My coral does not do well with a alk of 8- 10. My coral seems to thrive around 11-12. The alkalinity continues to want to spike up to 14-15. I do a water change to bring it back down, and in two days it is back up. I read that to increase the alk., you simply slow the effluent going through the reactor. To decrease, you would increase the effluent. I currently have the effluent coming out as a solid just before it turns into a drip. I have measured the effluent coming out and it reads 18. I have also been told that the effluent should be two to three times what you want in the tank. This isn't working for me and I need to keep this from fluctuating. It's having a major impact on my corals. If someone understands this very well, please assist me in stabilizing this in my tank. Thanks.