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Discussion Starter · #1 ·
I was dealing with the temperature rising to low 80s in my basement this past summer. I don't have any set up to cool my tank so the temperature in the tank was sometimes as high as 84.

My tank is a 240G with a 120G sump.

If I change the water out of the sump and replace with water that is more than 10 degrees cooler, will it harm the beneficial bacteria in my sump's biomedia?

I've been thinking of doing it this way so that it gradually lowers the temperature in the tank, causing less stress for the fish.
 

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When I have to use unheated water it is more than 10 degrees cooler.

I make sure I change 25% or less and all is well.
 

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I was reading up on this subject in a book by an Australian guy who uses small amounts of ice in his sump to cool the water. He cautions readers to keep the ice dose low and slow so as not to shock the fish, but I'd say if ice can be used safely, small water changes should be fine.
 

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A 10 degrees quick temperature change would be a huge problem for most fish. For beneficial bacteria it's a non issue. These bacteria are far tougher than most people think.
 

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Discussion Starter · #5 ·
fmueller said:
A 10 degrees quick temperature change would be a huge problem for most fish. For beneficial bacteria it's a non issue. These bacteria are far tougher than most people think.
Thanks fmueller. This is what I was looking for. By changing the water in the sump to cooler water, it would result in a gradual lowering of temperature in the 240G by about 5 degrees - which I imagine should be fine for my fish.
 

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I don't think if you change the water out slowly it would be problem. Some were around 20 gallon a hour.

If you change out 50% real fast you could lower your temp by about 5 degrees for half hour or more I doubt it would really make that much difference to the fish. I sure the lake goes up and down at times just the difference from top to bottom could be more then 5 degrees.
 

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The filter bacteria are tough, but they do slow down at cooler temperatures. If it's a significant difference, it might require a larger sump to get the same filtration. But ten degrees, I doubt will change much. Chilled cold water systems require a heat exchanger, so that the water going into the filter is warmed and the effluent water is chilled back to tank temperature. That could be three or four times what you are doing.
 

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Mcdaphnia is making a good point. In chemistry class, as a rule of thumb you learn that a temperature rise of 10 degrees doubles the reaction time.

That means if you lower the temperature by 10 degrees, you would need twice the number of bacteria to do the same job. Surface area is usually not an issue. As long as you have enough oxygen in the water, the bacteria should double in no time. Thankfully cooler water can dissolve more oxygen, so that helps as well.

Another factor working in your favor is that the fish's metabolism will also slow down at a lower temperature, and they will produce lass waste.
 

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fmueller;

Temperature will most certainly have an affect on filter bacteria action, but I must point out that you heard the 10 Deg/double reaction rule in Chemistry class not Biology class...so be careful about crossing disciplines and trying to bring along a rule of thumb like that...besides and as you note about the temp dependent fish metabolism, this is a complicated equation...

By the way, I sent you a private e-mail on or around the 24th...did it go into your spam, or are you just not answering me?

Cheers / Gruesse
 
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