Bubbling tap water is a waste in my opinion. I have heard from many reputable sources that bubbling tap water for even 5 days does not in fact remove chlorine nor chloramine.
Seriously? I can dispel that myth, and further clarify it for you. First, for chlorine (Cl) to offgas, you don't even need to bubble it, you only need to leave the body of water exposed to open air for about 24hrs. You can get a test kit and test this out for yourself, but I can also assure you that if it weren't true, fishkeepers wouldn't have been using this method for decades upon decades. Assuming you have some acuity left in your sense of smell (mine's compromised) then you can also simply use the smell test. If you smell Cl, it's still there.
Chloramine is a different beast, it's NHCl (chlorine bonded with ammonia) and that bond needs to be chemically broken. Most commonly used product in places like fish shops and public aquariums is dry sodium thiosulfate, which breaks the bond, dechlorinates and leaves the ammonia as a residue. Again, you can pick up test kits to determine for yourself how and that this does indeed work.
So, in short, aeration or just leaving in an open container allows Cl to outgas, but does nothing for NHCl.
I do like to pump air into my res using and air pump and air stones before watering as I feel the oxygenated water is appreciated by the plants.
I use R/O water myself and love it. I have a friend who does just fine though with striaght tap water. Many Organic gurus will tell you its not truely organic unless you are using R/O water though.
Another myth is that the air bubbles that are passing through the water column are, in fact, what is aerating the water (which really means helping or even forcing the O2/CO2 exchange to occur). First, it is only at the water's surface that this exchange normally happens (outside of a venturi). Second, even if using wood blocks as the 'stone', the kind that create superfine bubbles, usually the surface area is completely insufficient as to allow much of a gas exchange. What is really happening is that the bubbles are creating surface turbulence, and it is by this action that the gas exchange occurs on scale.
If they've appointed themselves guru, perhaps they should be questioned. I think everyone should be questioned, though.
