carbonic acid refers to the ph of carbon itself. it doesn't matter if it's diy co2 or pressurized co2, it's still co2 and acidic = carbonic acid. my statement is still relevant.I said when doing DIY, not pressurized. From what I have read, DIY CO2 produces carbonic acid that goes through the fittings and can cause them to erode more quickly. This is the same problem with using standard airline tubing, from what I understand. Again, though, that's just from what I've read.