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Minimum temp for bacteria growth

Hi All,

I remember reading somewhere that there was an optimal temperature for the bacteria in the system, and that below a certain temperature (65f ?) it ceases to multiply.

Does anyone know this to be true?

The reason I'm asking is that I'm planning a heating system for winter operation, and need a target for minimum water temps.

Thanks!

Paul

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Permalink Reply by TCLynx on August 29, 2011 at 11:53am

What type of fish are you going to be growing and how fast do you want to keep them growing in winter?

There are optimal temperatures for the bacteria and I expect there are minimum temperatures but they are not nearly as exact as the text books will tell you.

Remember that if you let the water temperature go down, the fish will slow down too so there won't be as much waste to process and as the water warms up slowly the bacteria will get going again but water quality and feed rates should be carefully monitored through that time if fish loads are heavy.

I've run systems where I let the water temp get down to 32 F and the system still functioned.

So It will depend more on what your goals are for the system over winter and what type of fish you will be growing. If you expect to keep tilapia eating and growing enough through winter to need full tilt bacteria function, then you need to keep the water at/above 70 F.

My Catfish still feed well when the water is in the 60-70 F range and I don't cut off feeding completely till the water gets below 50.

So, to me, the only real minimum temperature requirements in my mind are that you need to keep the water warm enough that it won't freeze into ice anywhere in the system that would inure the pipes or cause an overflow out of an iced up drain or bed.

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Permalink Reply by Paul Braun on August 29, 2011 at 12:22pm

Thanks for the reply TC,

I'm planning to start with catfish as they seem to have a wide tolerable temperature range (and I like the taste/texture;-)

Ideally, I want the system to maintain production through even the coldest months, but I know this will be a challenge in Michigan in Jan/Feb.

So it seems like the bacteria must do just like the fish and just slow down/stop growing below their ideal temperature, then kick back in when it warms up?