I've been lurking around here for some time now and I finally find the need to ask a question!! Every other time I've had an issue, I've found a thread where it was already discussed, but this time I have a new idea.
I am planning on starting Co2 on both my 10 Gal and 5Gal tanks using a DIY method for now. (too poor for any pressurized setups yet!

) I use Flourish Excel, but I have heard of some plants not responding too well to it (ie. melting under high doses) I have a Co2 Tester from Azoo, which shows that the Excel is working, but I have yet to see any pearling or even the growth that I am looking for and I hope that Co2 will provide this for me.
I'm planning on using a glass diffuser for the Co2, but I have an air pump set up on a timer that is opposite my light timer (light goes on, air is off, lights out, air kicks on, since I have been seeing some minor PH swings from night to day) If I keep that cycle going, and start DIY Co2, will the increased O2 from the air pump offset the Co2 diffusion at night enough so as not to cause an overall Co2 increase at night??