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Re: Losing corydoras :-(

Subject: Re: Losing corydoras :-(
by georgep56 on 2018/10/20 17:07:26

Quote:

Fishlady wrote:
There's nothing obvious from what you've said, except that 0 nitrate rings alarm bells. As the final product of the cycle, it's almost impossible to have 0 nitrates in a stocked tank. That may indicate that the cycle failed recently and produced ammonia and/or nitrite spike which killed the fish.


Thanks!

The 'zero' reading for nitrates is probably not 100% correct - our API Nitrate test kit has colour bands where yellow is zero and the next slightly orange band is 5ppm. The last test (taken soon after a regular 20% water change) was nearer to zero than to 5ppm, hence I put zero in my last post.

My wife has just been reading an article online which has made me think ... the tank has a lot of plants, wood and stones, which is a good habitat for the fish but makes it an absolute pain to clean the gravel. A week or so ago I did a 'deep clean' - moving all the stones and wood and cleaning all the gravel, which stirred up quite a bit of debris which the cories, by their nature, were foraging amongst. Do you think that it's possible that they have been 'poisoned' by being exposed to this debris? Should I be being more meticulous with cleaning the gravel? I have read elsewhere that having a build up of bacteria in the gravel as well as the filter is beneficial?

We've also been considering (prior to this disruption) fitting an external filter in place of the standard Fluval internal unit which has served us well since we bought the tank; obviously that won't make cleaning the gravel any easier but would you consider it a worthwhile upgrade? Would having an an external filter make the tank any "healthier" than an internal?

Thanks again!