Oxygen levels

[Dennis Bissett]

Hi Guys have read a lot of stuff about oxygen levels/aeration, Does anyone know of a way to measure o2 levels in the water apart from symptoms in the fish? Having no problems with my tanks at present but would be nice to know

[ScottishFish]

You can buy an O2 reader, I used one at a marine center I volunteered at, pretty expensive piece of kit though, as long as you can see some bubbles in your water then dont stress.

[bignellm]

+1 to the above.
The reciprocal would be to measure Co2 levels and might be a tad cheaper for the test (a Co2 drop checker I believe). Although, probably not to worry--your first sign of ultra low O2 as you point out in symptom form, would be fish gulping and gasping near the surface.