Removing the ice

[Kaniff]

I dont see any harm in this but I figured I might as well ask people with more experience... Is there anything wrong with removing the ice from my pond as its breaks up?

 

[Smaug]

Can't see why but don't see why.

 

[Becky]

I'm not 100% sure on this, but I think that when water freezes it expels some of the impurities - so the ice is actually purer than the water is comes from. So if you remove the ice, you are making the impurities more concentrated. However, on the scheme of things the effect is probably negligible!

 

[Meyer Jordan]

No harm at all.

 

[Smaug]

I'm not 100% sure on this, but I think that when water freezes it expels some of the impurities - so the ice is actually purer than the water is comes from. So if you remove the ice, you are making the impurities more concentrated. However, on the scheme of things the effect is probably negligible!

Sorta like just topping off instead of doing a water change

 

[Meyer Jordan]

I'm not 100% sure on this, but I think that when water freezes it expels some of the impurities - so the ice is actually purer than the water is comes from. So if you remove the ice, you are making the impurities more concentrated. However, on the scheme of things the effect is probably negligible!

If impurities are indeed expelled when water freezes, removing the ice would not concentrate these impurities as they are no longer in the ice but were expelled when the water froze. They are already in the water.
That point is moot because impurities (pollutants) remain frozen in the ice at the same level that they were in the water.

 

[Becky]

If impurities are indeed expelled when water freezes, removing the ice would not concentrate these impurities as they are no longer in the ice but were expelled when the water froze. They are already in the water.
That point is moot because impurities (pollutants) remain frozen in the ice at the same level that they were in the water.

Sorry, I didn't fully explain my reasoning: I accept that the level of impurities when there is ice in the water and after the ice is removed would be the same. However, when I said there would be a high concentration of impurities, I am referring to the water before the freeze vs the water after the ice has been removed.

Before the water freezes, you have some impurities in the water; After the ice freezes, the ice has a lower concentration of impurities and the remaining water has a higher concentration of impurities; If you then remove the ice, you are left with water with a higher concentration of impurities rather than allowing it to be diluted by the 'purer' water that had been frozen.

So if you compare the water before the freeze, and after the freeze, there would be a higher concentration of impurities if the ice had been removed.

We're splitting hairs here, like I said it probably only has a negligible effect anyway.

 

[Meyer Jordan]

When it comes to some pollutants, 'splitting hairs' may mean the difference between life and death for the pond inhabitants.
Whatever the level of 'impurities' in water before it freezes, this will remain constant as the water freezes. The resulting ice will have the same level of these 'impurities' as the source water.

Before the water freezes, you have some impurities in the water; After the ice freezes, the ice has a lower concentration of impurities and the remaining water has a higher concentration of impurities; If you then remove the ice, you are left with water with a higher concentration of impurities rather than allowing it to be diluted by the 'purer' water that had been frozen.

There is no scientific data to support the above quoted statement. Ice traps pollutants. This is why ice-cores are taken in the Arctic and Antarctic regions. These reveal valuable data on the level of various pollutants from different times in the distant past.

 

[Becky]

Thought I'd posted this article yesterday but it doesn't seem to have come through - it's an interesting read:

New technology purifies waste water by freezing it first: Possible applications in mineral extraction industry

 

[Meyer Jordan]

Thought I'd posted this article yesterday but it doesn't seem to have come through - it's an interesting read:

New technology purifies waste water by freezing it first: Possible applications in mineral extraction industry

Interesting news article. Thanks Becky. I would have liked to have had access to the actual research paper, but it is evidently not available. All the links provided by a Google Search of this article by name were to a manufacturer in China which incidentally tried to install Malicious Software on my computer. Glad that I have an anti-malware program.
I would like to see the scientific explanation of this claim. Until then, I will keep an open mind, but retain my original belief.

 

[Becky]

Agreed, there don't seem to be any accessible papers on it which is frustrating. The only thing I can find on this project is a summary on the LUT website:

When waste water freezes, it is purified - applications for the mineral extraction industry?

Perhaps they will release a paper once the project is complete in 2017? I hope they do, it's really interesting.

 

[Meyer Jordan]

I found this:
http://www.ncbi.nlm.nih.gov/pubmed/11747095
which, once one gets around the techno-speak, seems to say that it depends on the pollutant/impurity. If the pollutant is 'in solution' then it may precipitate out as the water freezes. Many pollutants, however, like Ammonia, Nitrite and Nitrate for example, are not considered in solution and therefore will remain as the water freezes. It evidently depends on the individual pollutant.
Still looking for a more definitive answer.

 

[MitchM]

I still have ice, so I thought I would thaw some out and test it a bit.
Here's a picture of water taken from the outlet of the pond breather compared to melted ice taken from around the breather.
The pond water is in the glass on the top.
I took a TDS reading of both, the pond water was 122, the melted ice was 21.
What I found most interesting was the amount of dust and debris (including some bug parts) contained in the ice which of course won't make it into into the pond until it melts.

Perhaps the sudden influx of dust into the pond during the spring melt is a contributor to spring algae blooms.

Regarding the difference in TDS readings, I can't be sure how much of the ice is made up of fallen snow (which will have a low TDS content) and how much of it is pond water.

 

[Meyer Jordan]

I wonder what differences there would be in test results of other parameters such as Ammonia and Nitrate.

 

[MitchM]

Ammonia pond water 0
Ammonia ice melt 0.25
Nitrate pond water 0
Nitrate ice melt 0

Which makes sense since there would be decaying organic matter caught in the ice and no sufficient bacterial population to break the ammonia down.
It looks like the ice on top of the pond is essentially a nutrient bomb that will release excess nutrients into the pond as it melts.