Oxygen Circulation

[Bronx19]

Does having all lids on the aquarium create an issue with oxygen diffusion?

With the lids on, there are only the corners (airline access) open to the air, and I have noticed that in winter especially, I can feel warm air rising out.

[oscar]

It does have an effect. I've never seen it quantified.

It's mainly linked to the circulation. Obviously the diffusion at the water/air interface is unimpeded, but there is potentially less oxygen available at the water surface to be diffused into the liquid. This because the gasses that are being given off to the air by the water are somewhat trapped in a mocro-environment. You can reduce the effect by maintaining a reasonable gap between the water surface and your glass lid.

Plenty of people run lids, and they certainly have their benefits in terms of heating efficiency and evaporation control.

I personally don't use lids as i feel the transmission of light through the glass, especially when it gets a bit of calcium etc build-up is impeded.

[Bronx19]

I can vouch for the evaporation, the amount of water I lose out of my 350l tank is quite alarming at times.

[Phlipper]

I've never noticed any problems with close fitting lids on all my tanks ?

But I wouldn't do without them, and the less gaps the better, apart from evaporation and better heat control, they will save the life of that extra precious fish should it decide to do the leaping Salmon trick.

[oscar]

Qualify my previous stament in regards to fish jumping out.

I have lights and a timber hood. I do not have glass lidds between the water and the lights.