It was something I thought I remembered reading from somewhere. I know nothing about adding o2 to aquariums but know that, as with everything, balance is the key. I wondered whether there was more oxygen at the top levels than the bottom. Besides which, when you said o2 I was thinking CO2 being added for the plants. Probably totally off the track :oops:
Having the kuhlis in the top of the plants is one thing, having them there as they appear stressed is another