DOC and foam fractionators...

[JohnHuff]

So I've been reading a lot of threads recently and dissolved organic carbon (DOC) is something that I rarely see talked about. When you read posts in this forum about water problems, it's always about nitrogen based compounds, pH or KH, but rarely do people talk about DOC.

So how important is DOC in freshwater ponds and should we be worried about it? I'm thinking that might be the missing key to all our ponds. I built a mini ff when I first joined this forum but it was too tiny to form bubbles but I think it can be done easily with a small pump and some PVC pipes.

 

[crsublette]

From what I am aware about, as I called it "dissolved organic particulates", other call it DOC as you have describe, this pollution is only a concern much like Nitrates, that is it is only a concern when the concentration becomes extraordinarily high. Other than this, until it gets to this point, DOCs will create an aesethically displeasing appearance of a constantly present brown foam buildup on the pond's water surface.

I have had a bit of foam over the months, but nothing too bad and it would all just end up in my skimmers, where I would scoop it out.

Foam is created due to the water's increase surface tension. Salinity increases water's surface tension. The lower salinity content in freshwater is why it is tough to make the bubbles. As a result of increased surface tension, bubbles are formed and dissolved organic particulates are attracted and trapped into the bubble's surface tension. So, a pond can have a high foam content and still have a low dissolved organic particulate concentration.

As far as I am aware, the threat of a high DOC content is it persuades the growth of heterotroph bacteria and other similar organisms that feed on DOCs and this increases biological activity causing more consumed oxygen out of the water, which is not a problem as long as the water is properly circulated.

Here are a few references to some DIY instruments built to address DOCs:
Post#22 in thread "UV or not UV"
Protein Skimmer

I do not have a FF simply due to my laziness and procrastination. :cheerful:

 

[slakker]

I've been curious about these myself. These are a must in any marine tank if you ask me and I run them in 2 of my three tanks (the 3rd is a small 14G nano that I can't fit one in so it's more frequent water changes).

I was talking to a local pond guy and he mentioned that if you run one for a pond, running the water with about a 1% salt as Charles mentioned. At 1%, none of the plants should get affected so it's a good compromise. He also noted there could be some secondary benefits of salt, but may be a bit too low concentration to fight diseases.

The other thing we run with skimmers is Ozone, we inject it right into the skimmer to help with water quality as an alternative to UV.

 

[Mucky_Waters]

I do not have a FF simply due to my laziness and procrastination. :cheerful:

Well, due to my industriousness and lack of procrastination I do have a phoam phractionationer (aka protein skimmer). :banana:
However, I don't really know how necessary, or even helpful, it is in my pond. I mainly set it up because I had a separate pump for my skimmer anyway and want to run some sort of extra filtration on that line. I also liked the trickle tower bio media portion of the phractionator, so even if it's not producing foam I still have some auxiliary bio filtration. And quite frankly, it doesn't produce foam much of the time. This could be due to a few factors. One being that the FF tends to produce foam under certain conditions, those being there has to be a higher level of DOCs to start with. Also the weather conditions have to right, too hot and production slows or stops completely. I've noticed it produces foam better while we have rainy weather, this could be due to it being cooler and more conductive to foam production, or it could be as I suspect, that the soft rain water also has something to do with it. (softwater = more foam)
Going back to the DOCs levels in the water, another way to lower those levels is simply do frequent water changes. When summer starts I run a constant drip flow through water change. This constant water change is probably another reason I don't get much foam production in the summertime, the DOCs level just isn't there.
My best foam production happens in the early spring with cooler weather, high DOC levels from the algae breaking down through the winter, and no drip water change hooked up yet.

Of course none of this addresses Johns original question "So how important is DOC in freshwater ponds and should we be worried about it?" ... On this I tend to agree with Charles "this pollution is only a concern much like Nitrates, that is it is only a concern when the concentration becomes extraordinarily high. Other than this, until it gets to this point, DOCs will create an aesethically displeasing appearance of a constantly present brown foam buildup on the pond's water surface."

 

[slakker]

If nothing else, you got really REALLY good water aeration! LOL...

 

[JohnHuff]

Thanks for your answers. I have been thinking about it also because with the many bio-filters and plants we have in our indoor tanks and with the plants in the pond we have become lazy about changing the water. 1 week has stretched into as much as 4 weeks, thinking that nitrogen compounds is all I need to worry about. There is no excuse for not changing the water in the pond because it's as easy as switching on an auxiliary pump and then adding more water.

 

[Mucky_Waters]

If nothing else, you got really REALLY good water aeration! LOL...

Yeah, that too.
So extra bio filtration + aeration + DOC removal some of the time. What's not to like. :biggrin:

 

[crsublette]

I've been curious about these myself. These are a must in any marine tank if you ask me and I run them in 2 of my three tanks (the 3rd is a small 14G nano that I can't fit one in so it's more frequent water changes).

I was talking to a local pond guy and he mentioned that if you run one for a pond, running the water with about a 1% salt as Charles mentioned. At 1%, none of the plants should get affected so it's a good compromise. He also noted there could be some secondary benefits of salt, but may be a bit too low concentration to fight diseases.

The other thing we run with skimmers is Ozone, we inject it right into the skimmer to help with water quality as an alternative to UV.

I said absolutely nothing about a 1% salinity and I did NOT suggest a mention anything like this.

With freshwater fish, a 1% salinity is lethal in long duration dosages and only recommended for extremely short duration dip to act as a parasiticide.

 

[slakker]

I said absolutely nothing about a 1% salinity and I did NOT suggest a mention anything like this.
With freshwater fish, a 1% salinity is lethal in long duration dosages and only recommended for extremely short duration dip to act as a parasiticide.

Sorry, my inference wasn't clear... It was to your comment that salinity increases foam creation... Not that you said to run it at 1% salinity.

 

[Dave 54]

Thanks for your answers. I have been thinking about it also because with the many bio-filters and plants we have in our indoor tanks and with the plants in the pond we have become lazy about changing the water. 1 week has stretched into as much as 4 weeks, thinking that nitrogen compounds is all I need to worry about. There is no excuse for not changing the water in the pond because it's as easy as switching on an auxiliary pump and then adding more water.

John we have a home made one , damn good at its job to/

rgrds

Dave