C02 Scrubber...... First this does not take the place of a balanced alk, cal, mg issues but if all your levels are good and your ph is still low a C02 scrubber may be the solution. I've delt with low pH for a while. It started when I changed from 2 part to a Calcium Reactor. So why not stay with 2 part, you may ask, well that could be a whole new thread but I was very happy with 2 part but like the benifits of the Calcium Reactor. So I've been dealing with low pH and was really not sure how to fix my problem. I did get a degas chamber for the reactors effluent thinking this would solve the issue but it seemed to do nothing. Then I added more Kalk to the stirrer and that did help elevate the pH along with the alk. Then I read about a C02 scrubber, bought one and its working great. I was dealing with a nightly ph of 7.7 and a daily high of 7.9. Forgot to mentioin I also have a fuge with macro and do reverse lighting. So I got everything from bulkreef and it was an easy hook up. Basicly its a airline that comes off the vinturi of the skimmer, same as if you ran a line outside, to a reaction chamber that has an absorbent for C02, the absorbent changies color when its used up. So I hooked it up with everything from bulk reef. The line seemed small and the elbows leading into the reactor also seemed small. So I hooked everything up and noticed my skimmer did not seem to be working properly. I called tech support and they told me to take off an elbow from the inlet side or use an air pump to force air into the system. So I did that and then measured the AirFlow of my skimmer and it was still reduced almost 50%. I then made a trip to lowes and bought a larger elbow and tubbing, I think 3/8" ID, and after hooking all that up my Air flow is great and my pH over the past 24hrs has been 8.24 at night and 8.31 during the day. So I"m very happy with the results. Also there are plenty of DIY C02 scrubbers that would work fine I'm just one of those people who has to have everything uniform.....