Oto, I Hardly Knew Thee

I unexpectedly found one of the otos lying dead and discolored in a crevice of the large driftwood piece today. I'm not quite sure what happened. The nitrates are down in the 10 ppm range these days. I'm hoping it's just one of those things, and not a bellwether of things to come. I have no desire to potassium poison my fish or anything like that.

A couple pieces of good news:

1) The tail of at least the cory that was medicated is visibly showing new growth as it presumably heals.
2) I can't be sure that the kuhli loach is completely better, but I was heartened to see them both for the first time in a while, intertwined in the upper parts of the rotala indica.

Still no iron detected by my iron test. I'm beginning to become suspicious that the test is bupkus. Either that, or my plants or eating it up at an unconscionable pace, especially considering I never specifically dosed with iron in the past. At this point, I don't think I have any choice but to keep it up for now.

I've noticed plant growth slowing down a bit (the baby hornworts are a good way to gage the pace), but the CO2 canister is probably at the end of its line, so I'm hoping any slowing of growth is due to reduced levels of CO2 in the water. The pH was measured at 8.0, so that supports my hypothesis.