Dosing Bacteria Increasing temperature

[Davisc1293]

I've noticed the two times I've dosed eco balance the tank got much hotter then it normally does. It was interesting to see on the graph the two nights that I dosed eco balance the tank got as much as .8 degrees warmer then normal. I know .8 degrees is not a big deal but on an average day my tank is pretty tight and doesn't swing more than .2 or .3 degrees (78.7-78.9) occasionally ill see 79 but a small fan comes on at 79 until its back down to 78.8. The first night I dosed eco balance the tank got as hot as 79.8 and mind you that's with the fan on which I've found pretty effective in the past at cooling the tank back down. The same night the ph got a bit lower then normal which is the part I do sort of at least understand what's going on with the bacteria consuming more oxygen leaving more C02 in higher ratios ect ect.... but to generate some serious heat (the fan was on and the tank still got almost a degree warmer where it normally doesn't swing more the .2) It was more of an observation I thought was worth sharing but it opened my eyes to the need to understand these different bacteria's I use so liberally.

 

[taricha]

hmmm....
As interesting as this would be if it were true, it seems like it has to be coincidence, fluke, or faulty measurement.

I mean I can imagine some exothermic chemical and biological processes, but that's a lot of energy released by an additive. Just seems really unlikely.

 

[Davisc1293]

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[Davisc1293]

 

[Davisc1293]

hmmm....
As interesting as this would be if it were true, it seems like it has to be coincidence, fluke, or faulty measurement.

I mean I can imagine some exothermic chemical and biological processes, but that's a lot of energy released by an additive. Just seems really unlikely.

I agree with you but I find faulty measurements unlikely just because how consistent the tank has been running (as far as temp/ph) and the two nights the temp increased like this was the first two nights I dosed eco balance. I believe it said to dose 1 cap per 10 gal so the first time I only did one cap. After seeing that the temp and lower ph I figured I caused a bacterial bloom so the next night I dosed a little less then full cap and the same thing happened yet not as drastic. Ill keep you posted how the third dose goes. But the tank seems to be back in its normal swing after a day. Im not going to dose tonight and ill see if it stays at the normal 79 and will dose again tomorrow.

 

[Dan_P]

hmmm....
As interesting as this would be if it were true, it seems like it has to be coincidence, fluke, or faulty measurement.

I mean I can imagine some exothermic chemical and biological processes, but that's a lot of energy released by an additive. Just seems really unlikely.

Agree.

While heterotrophic bacteria generate heat, unless the concentration of bacteria and nutrients is high, detecting it at such high dilution in an aquarium would seem unlikely. Also, why is this happening only at certain times? You might look for a correlation with a mechanical or electrical device. Also, home temperature variation will have an effect on water temperature control.

 

[Hans-Werner]

If it would be reproducible and not pure coincidence I had an alternative explanation.

I also think it is very unklikely that the dosed product generated so much heat. Most likely the caloric value is not high enough to heat so much water, even if it would be converted into heat by 100 %.

Here my alternative explanation: What if it didn't generate much heat but just prevented cooling. A thin film of lipids or something else floating on the surface, reducing evaporation and in this way preventing effective cooling could also cause a higher temperature than normal. Would this be plausible with your setup?

 

[Randy Holmes-Farley]

The evaporation prevention is certainly plausible to me if the surface water is not readily skimmed by an overflow, etc.

Generation of enough heat by metabolism of organics to actually detect is probably not the explanation, but one can assess the upper limit of what might happen by gauging how much heat might possibly be generated.

let’s assume every bit of organic carbon is instantly converted into CO2. How much might that raise temperature?

Let’s be wild and assume tank water contains 20 grams of dry glucose in a 100 gallon tank. That’s 20 g/378 L, 0.053 grams per liter. That’s 53 ppm of super easily digested organic, or 21 ppm TOC. Real measurements of reef tanks show more like 0.5 to 5 ppm TOC, and much of that won’t be so readily digested.

The heat of oxidation of glucose in water is about 2078 KJ/mole.

0.053 g/L is 0.053 g/L / 180 g/mole =0.00029 moles/L

Thus we generate 2078 kj/ mole x .00029 moles/L = 0.6 kj/L.

The heat capacity of water is 0.4 kj/L per deg C.

Thus, we’d see about a 1.5 deg C rise. this is obviously intended to be an overestimate, but shows that a rise of 0.5 deg C, as seen above, cannot be totally discounted, but is probably significantly more than would be expected.

 

[Davisc1293]

Im only home for about an hour a day to feed the fish, shower, and head to my gfs house to eat and sleep so dont get back home until the next night. So i got home at 930 after work both nights, and dosed eco balance at the same time. Last night i did not dose and did not see an abnormal swing. I will dose more tonight and see if this is repeatable in my tank.

 

[Crustaceon]

Maybe the additional bacteria is temporarily coating the temp probe, slightly insulating it and acting as a “blanket”, causing a slight temp increase localized at the probe?

 

[Hans-Werner]

I want to test a different approach in calculation, partially using the numbers from Randy which will make the work much easier.

A high normal vodka dosage for daily vodka dosing is ca. 10 mL per 1000 L. Twice the dosage may cause massive bacterial blooms and oxygen depletion. Vodka is ca. 40 vol.-% ethanol resulting in an ethanol dosage of ca. 4 mL per 1000 L or 3.16 g/1000 L.

3.16 g C2H6O = 68.6 mmol C2H6O per 1000 L or 137.2 mmol C per 1000 L.

The same organic carbon dosing is achieved with 22.86 mmol glucose C6H12O6 = 4.12 g Glucose.

At 2078 kJ/mol (= 2.078 kJ/mmol) the energetic value of 22.86 mmol C6H12O6 is 47.5 kJ.

With a heat capacity of 0.4 kJ/L per deg C, 47.5 kJ is sufficient to heat 1000 L of water by ca. 0.12 deg C.

According to my calculation it is unlikely to achieve the observed temperature increase of ca. 0.44 deg C with a dosage of labile organic carbon that would not cause serious adverse effects if dosed daily.

 

[Davisc1293]

I took a break from dosing anything for a few days and my apex has shown the normal 78.7-79 swing for the last week. Last night I decided to dose eco balance again but this time a slightly larger dose (2.5 cap fulls) And I did see another small spike in temp up to 79.5 so is reproducible even if it is something else happening. This post was more to just document and share my observations I found interesting.

 

[Randy Holmes-Farley]

I took a break from dosing anything for a few days and my apex has shown the normal 78.7-79 swing for the last week. Last night I decided to dose eco balance again but this time a slightly larger dose (2.5 cap fulls) And I did see another small spike in temp up to 79.5 so is reproducible even if it is something else happening. This post was more to just document and share my observations I found interesting.

Thanks for the update!

 

[taricha]

Last night I decided to dose eco balance again but this time a slightly larger dose (2.5 cap fulls) And I did see another small spike in temp up to 79.5 so is reproducible even if it is something else happening.

did you look at pH this time too? pH dropping lower at night and increased temp might be consistent with this explanation....

What if it didn't generate much heat but just prevented cooling. A thin film of lipids or something else floating on the surface, reducing evaporation and in this way preventing effective cooling could also cause a higher temperature than normal.

 

[Davisc1293]

yes. Just like the last two times that I dosed the product, at the time the temp was at its highest, The PH was at its lowest (lower then normal as well) usually it drops to about 2.25-2.28 at night. last night when the temp hit 79.5 (.5higher then usual) PH was at 8.23 (.08 lower then "normal") However the fan I use to cool the tank is pointed at the water that's overflowing so there should not be any film on that fast moving overflow.

 

[Davisc1293]

blue is temp orange is PH