I been messing around with the ph problem for the last year or so... I have even considered going back to 2-part but it's just not practical since my water volume is close to 500 gal. If your tank is 150 gal and below go back to 2part dosing, it's easier and no low ph problem. 2-part will do everything you are looking for.
Here's what I went through..
- Before the big tank upgrade I was doing 2-part dosing, everything was perfect, had ph of 8.1-8.3 stable alk/calc. Acros grew insanely.
- Tank upgrade 2-part just didn't make sense... so I switch to calx, ph drop to 7.6-7.9. Alk/calc was stable but my corals SPS just stopped growing.
- Figure it had to be my ph, so I added air bubble in my sump area to increase agitation and gas exchange but that didn't do anything...
- Tried venting the room, open windows, fans and even an outside airline for the skimmer.. ph went up to .1 didn't do much.. even got a co2 monitor and readings were fine.. 400 range, so it wasn't the surrounding air.
- Since the air around the room wasn't saturated by co2, I had to do something within the tank... started out with a Kalk stirrer. I had this setup at max capacity. I was topping off about 5-8 gallon of fw everyday, so I set my peristaltic pump to pump 5 gal of kalk into my system. Tuned down my carx. Ph went up to 7.9-8.1.
- Ph of 7.9-8.1 would be fine.. but since I'm on the path I'd figure I would give co2 scrubbing a try. When i first started with the co2 scrubber I was replacing the media weekly. ph went up to 8.1 - 8.3. Ran the co2 reactor for a few weeks before I decided to try the re circulation method. Media now last me around 17-19 days. Which worked out for me.
- Out of curiosity I turned off my carx for 1 day just to see what my ph would be like with all the new implements... my ph shot up 8.5 and it kept climbing.. I quickly turned off my skimmer to let my ph drop back down.. even without the co2 scrubber that day, my ph stay around the 8.4 during day time.
So if you don't want to go through all of this, 2 part dosing will solve your ph problems =)