Hi everyone, I've recently (and reluctantly) gone a bit more high tech and added a CO2 unit to match my high-ish light output. I bought the D-D unit online and should have received a simple bubble counter/diffuser in one to sit inside the tank (that's what is shown on the website I bought it from and on D-D's site). However, when it came it turned out I had the bonus 'Turbo' unit. Which is basically a small power head that CO2 is fed into from the now external bubble counter/diffuser. I have placed this power head just above, and firing down into, my filter outlet. The power head fires out CO2 micor bubbles and the filter outlet distributes them. The trouble is my CO2 levels are not rising (or rather my pH levels are not falling) and the surface of my tank is completely awash with micro bubbles. My questions are: Do other diffusers that produce micro bubbles cause this on the surface? Has anybody heard of this kind of system? Should I change it for a normal diffuser placed under the filter inlet? Am I being impatient with the whole thing? (It's only been running properly for two days due to timer problems) Also, I have the Tetra Optimat on my nano and this is doing nothing at all. I see no bubbles of any kind and the pH is rising despite me filling the unit three times a day. Anyone got any experience with this? Any advice?