Dissolved Organics

RupertofOZ

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DOM is made up of any carbon compounds (contain at least a carbon and hydrogen atom) that are dissolved in water... (edited)

So it would seem to me that if the compounds are waste that nothing can use then they're pretty much non-reactive right?

Couple of points, both carbon and hydrogen are the two main building blocks of nature.... because they are so readily "reactive" and will either make or break molecular bonds in most other compounds.....

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Also, in an aquaponics system we're constantly removing organic matter from the system in the form of fish and plants, so maybe this is where a lot of this stuff goes...

Here's the crux of the matter I feel and the point which may be lost on your friend... yes we are removing organic matter from the system in the form of fish and plants. But we are doing it by the "reactive" breakdown of these compounds by the Nitrosomonas and Nitrobacter bacteria ... the most crucial component in the cycle and a process that does not take place in aquaria or even in aquaculture systems because the nitratres and other trace elements and DOM aren't removed by the uptake of the plants and the bio-filtering process of the growbeds which we utilise in AP

This is the crux and the crucial difference between AP and aquaculture or aquaria system. Those systems deal with DOM by foam fractionators, protein skimmers, external bio-filters and constant water changes...

We don't have to..... the natural processes occurring in the growbeds deal with the problem, just as nature cleanses a natural waterway... or as can be seen even polluted waterways ie. reed beds.

hydrophilia

mrgrackletx wrote:

Commercial sized systems would probably be fine.. main reasons is they would use plants for nitrate breakdown, carbon for dissolved organics removal, and top-off for nutrient replenishment.. This is fine, for a commercial sized system. The top-off nutrient replacement, when losing hundreds of gallons of water each day from evaporation, is more than enough to constitute keeping the alkalinity up in the water..

In a small home-based domestic aquarium, not so much the case. 2-3 gallons of top-off water is simply not enough to replenish the needs of a well-stocked home aquarium.

Hunh?? It is proportionately and chemically the same, I think.

mrgrackletx wrote:

The dissolved organics I am worried about, are dissolved organic compounds.. (DOCs) The waste product of fish that can not be broken down by the nitrogen cycle, and can only be removed through resins and water changes.

I have heard of alot of 'self-sustaining' systems before.. It seems the larger the system, the more self-sustaining it can be.. I know that the large aquaria in Nevada's casinos does not do water changes, but only replaces lost evaporation water. However, their tanks are filled with sickly looking fish, very high nitrates, and the longevity of the fish in their care is shortened compared to large scale aquaria that performed water changes. Hole in the Head and Lateral Line Erosion is a very common disease in these large public aquariums that don't change water frequently.. lack of minerals.

I've read about a fellow who recirculated various polluted water through a series of tubes (no, not the internet, Senator Stevens!) and found that biological communities sprang up that fed upon and broke down any DOC that he put in. These communities changed and reconfigured depending on what he ran through the system. Unfortunately it was pre-web and I don't have the ref, but the point is that, unlike the small-filter (probably) aquaria at the casinos, the aquaponics growbeds are huge surface-area filters with a diverse biological community that evolves to eat any fine particulates or DOCs the fish send it.

If the casinos ran their aquarium water past their plants they would have healthier plants and fish (ignoring factor of drunken patrons finding bathrooms too far to bother....and smokers disposing of their toxic butts. "baccy is a good pesticide, but not a good aquarium amendment))

Daniel

I found this the other night which seems to fit in with this discussion:

article

I abstractly read it as, the biofilm on the gravel/growbed medium is better then many other forms of mechanical filtration because it attaches to the small particles as well as trapping the large particles. Doesn't specify how small the "small particles" are though

Sleepe

Hate those buy the article sites.

Appears it has gone into commercial production however

http://www.expo-net.dk/sw289.asp

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Dissolved Organics

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A place to discuss aquaponics