Ty. I was having a very similar and frustrating experience. I would go through an entire canister or media in a week. As adding the water bottle to the inlet of the reactor significantly improved the length of time you can get out of the media?
Ok a side note.... I can also say they sometime a scrubber can be too much of a good thing. Again like you I was fighting chronic low pH on my tank so I threw a scrubber on. It worked great besides the whole change the media every couple of days thing... which on a further side not can be a major pain if you have a dosed set up. As the media begins to exhaust the demand for alkalinity starts to drop, the doses isn't smart enough to recognize this keep dosing at the same amount and you alk numbers start to rise. Bad news there.... anyway back to the original thought.... scrubber works great when people and pets are in the whole maintaining a fairly consistent level of CO2. But then you go away for the week on vacation. That normally level of CO2 isn't in the house and that is where the trouble on the flip side of the coin begins.
Now fore this isn't a theoretical, this happened just a few weeks ago. In an affront to maintain consistency while I was gone on a business trip for 10day I replaced my media the day I left. I was trying to avoid the situation that occurred during the last trip where the media exhausted and my alk spiked, sps melt down... Any way fresh media is on the system, I walk out the door all is good. My wife and dog also decided to go stay with a friend while I was away. Through my controller I am keeping track of my tank while I am half way around the world. First the first few days everything is good and the pH is stable around 8.3. A couple days later the pH starts to climb. 8.40, 8.45, 8.50, and finally settles on 8.55 where it remains until I get home. First thing I do is look at the media and find that it is now where as near as exhausted as it normally would be for close to 10 days. Alk check shows that my level had dropped significantly even though the dosing pump was functioning properly. This is just the opposite of what happened before where pH dropped alk consumption drops. PH raises alk consumption raises. It makes it impossible to set a doses to take care of your additions with this kind of swing and stresses your corals. Anyway I don't change the media and continue to monitor pH of the next couple of day now that people are back in the house. And what do you know it settles right back to between 8.2 and 8.3.
All in all I almost think it is better to have a much lower base pH than deal with the swings that can be introduced by a scrubber. I have since taken my scrubber of line and and experimenting with a hose run out the window. It's not pretty looking but the pH is stable, and it is a great big world out there full of oxygen.
