Lost an oto today I was getting ready for work and when I checked the tank I noticed it's tail stuck in the intake grills. I unplugged the filter as quick as I could and reached in to release him, but it was too late.
I took this a few minutes ago. CO2 has been increased to combat some algae growth. Over time, the cheap diffuser doesn't produce a fine enough mist. Large bubbles were being shot out and reaching the surface before being moved around the water column. Even after a cleaning in a bleach solution overnight, the diffusion was inadequate.
I swapped in another one (I have several, as they are only a couple $ each), and the new one is much better. Quality control is not to be expected for the cheap stuff.