Absolute Max Temp For Cycling?

[ellena]

I know about 30 is optimum, but how high before the bacteria start to die?

 

[Geoff1991]

Interesting question, i would also like to know the min temp as im wondering if i can do my large water change with just cold water...

So, free bump for you.

 

[waterdrop]

My take, for what its worth, from reading all of Hovanecs papers and from many searches and threads here from over the years is that its a more complicated picture than we usually talk about. First of all its important to keep it in context: In the overall scheme of things, water temp is not acually a huge factor in the bacteria growing, its a bit more of a detail, but its significant enough that we certainly like to try and make use of it for its possible contribution to a little speed up.

To answer Geoff's first, I'm sure there is some very cold temp at which you would simply not get activity out of our two autotroph species, but I don't know what that is and its sure to be below any common cold household temp we'd have, so even if you're not heating, these two species are going to slowly grow.

The upper temp recommendations come from many, many reports ever since fishless cycling got going in the 1980's and are generally up around the 30C that you are citing ellena. RDD himself has made pretty many comments on TFF regarding this and has even mentioned he continued to hope to try some experiments some day of even higher temps to see if he could discern any added advantage.

For my part, somewhere in all of Hovanecs stuff, I remembered reading at some point that there might be a bit of a problem in that of course what's really going on is that there are a whole crop of different species in there fighting for space on the prime ammonia/oxygen food spots in the filter biomedia. I wish I had documented it now, but what I remember was reading there might be a bit of a problem encouraging the wrong species as you get warmer above about 29C/84F and this is why I quote that so often as ideal. I remembered it as a similar thing to the more definate Hovanec advice that 8ppm of ammonia encourages for sure a particular different "wrong" species. In practice, I'm sure it would be extremely difficult to prove this to any degree of reliability, but anyway, there you have it. If I ever run across a more concrete reference in my re-readings of Hovanecs papers or, as a long shot, actually get him to reply to anything, I'll be sure to post it.

Finally, as to what high temp might -kill- Nitrosomonas and Nitrospira, I don't have that info.

~~waterdrop~~

 

[ellena]

Even if a high temp wouldn't kill the 2 bacteria we want, the fact that it would encourage the wrong type is enough reason not to do it.
I'll wait until my new heater arrives-Thanks