Anerobic activity Good/Bad

[angel12]

I have come across an article which looks at anerobic activity
In the case Planted Fish tanks it mentions the "smell" of the water in that if it smells sulphuric.."like a struck match" then this is an indicator of Anerobic activity ... my point is what is anerobic activity? is this good /bad if bad what detriment does it do to the tank and how can it be avoided what causes it .. my guess is more water changes is this right

if anyone could enlighten me I would appreciate it

[ronrca]

anerobic is the opposite of aerboic. Basicly your going backwards in the nitrogen cycle.

aerobic - ammona-nitrite-nitrate
anerobic - nitrate-nitrite-ammonia

Anerobic conditions apply where there is a lack of 02 like under thick gravel with little or no water movement. Bacteria is very amazing. The bacteria use an oxygen atom from nitrate (N03) and therefore produce nitrite (N02) This process is used a lot in treating sanitary waste.

Links:
http://www.ntlabs.co.uk/Lower_nitratesP2.htm
http://www.nishihara.co.jp/english/pdf/anaerobic.pdf

[ChloroPhil]

Angel12,

Anaerobic activity isn't good in a planted aquarium environment. You want your substrate to be getting sufficient circulation and oxygenation to keep anaerobic activity away. If you're having trouble with that I suggest putting Echinodorus or Cryptocoryne plants around your tank to create a network of roots to pull water through your gravel.

[angel12]

Cheers Guys ;D However Bio you do not mention what negative effects this has on the Tank .... I have often wonderd what this sulphuric smell is caused by (not in my tanks but others I have water changed) now I know but as above what are the downfalls if this situation is allowed to continue

:)

[ronrca]

Very good question! Why is it bad?

Im not sure! From reading articles about anaerobic, it doesnt really mention why it is a bad thing. In a planted tank, the plants will be using up the ammonia, nitrite and nitrate. It doesnt really matter if its going thru the aerobic cycle or the anaerobic cycle.

Now, if we take a simple approach to this question. Lets think about the substrate and take a 3" substrate. If you do not use a undergravel filter, you are not getting any water flow thru the gravel anyways. Therefore, imo, most tanks with a substrate (depending on the depth and density) will have some anaerobic activity.

So, back to the original question, is it good or bad? I would have to say that its part of the whole ecosystem of a planted tank where both 'cycles' are working together.

Take a look at the diagram:
http://shell.pubnix.net/~spond/filter/nitrogen.html

It this situation continues! Well, I think it depends on the tank. If its planted, should be no problems as the plants will use the nutrients plus the aerobic will also be working. If you dont have plants and lose the aerobic filter, well, you go back to the ammonia stage.

oK! I did some digging! This process of dinitritification produces nitrite, nitric oxide, nitrous oxide and hydrogen sulfide.

Here is a long article about denitrification:
http://www.ece.eng.wayne.edu/~hying/images/AE%20squid%2000.pdf

[brewmaster15]

Hmmm... my concerns on why its not good to have anaerobic activity in a tank with fish...Not sure how many of these are valid, but it how I look it.

1) its an indication that there may be insufficient oxygen in the tank to support healthy colonies of aerobic bacteria required to break down the ammonia to nitrite-to nitrate.This could set you up for a serious ammonia spike/nitrite spike.
2) Nitrites, even low levels are toxic to fish, so if if you constantly have them being produced by both types of bacteria... you could have some very unhappy fish, especially if there are any disturbances in the tank.
3) Fish gills are sensitive... hydrogen sulfide... not a good combination. Talk about acid rain.. ;D
4)heres the real controversial one... The basic problem with undergravel filters was that they gave organics a place to accumlate. This gets clogged in a poorly maintained UGF system, and the result is anaerobic. Historically...Discus don't seem to like these systems ... probably because they do usually promote anaerobic bacteria production... in the poorly maintained tank. ...Its one major reason why UGFs are looked down on in tanks with discus.
5) Its an indication that excess organics may be in the tank, and creating these anaerobic pockets .. Those organics are food for pathogenic bacteria.

I'm sure there are others, but these are the things that come to my mind...at least in relationship to Discus.

hth,
al

[ChloroPhil]

Brew already mentioned it...Hydrogen Sulfide. That'll take out a fish quicker than just about anything in an aquarium. Also, anaerobic patches are bad as they tend to spread and will damage the root systems on your plants.

If you want to get really nifty and make the Deep Sand Bed argument, then anaerobic patches are ok. Just dump at least 7" of gravel in your tank and let all the crap settle to the bottm where you'll never, ever get to it. They say that the bottom layers naturally reduce Nitrogeneous compounds, but I'm skeptical.

Needless to say I'm not a big fan of DSB, most of the marine systems I've worked on with them have had problems because of them. I'd rather keep a nice 2-3" bed with a lot of vigorous root activity and a mess of Malaysian snails rooting around in it. Or, if you're techincally inclined get an Under Gravel Heater cable like Kaspar Horst recommends (and sells).

[ronrca]

Good! I didnt know the effects of Hydrogen Sulfide.

Now, about the substrate! My substrate is river gravel, 4-5mm plus flourite mixed in. Its about 3" minimum to around 5" max! When I look at it, there cant be any water movement thru it because where will the flow be coming from? I would have to think that there has to be some anerobic cycling going on. I guess the important thing is that it does not get too much! I would be really interested in finding out how much anaerobic is actually taking place. This anaerobic is only taking place in the bottom 1" I would think! So, maybe above the anaerobic there is the aerobic because of more access to 02! Just a thought!

[ChloroPhil]

Ron,

A strong root system can pull as much as a liter of water into the gravel in a day. Even a gentle, steady, flow of oxygenated water will keep the anaerobic patches away. George Booth once had a three year old sword plant with a root system that took over the entire bottom of his 90g. It took three men to pull the thing out. Imagine what those roots were doing for his substrate? Other than taking it over....

[ronrca]

REALLY? :o WOW!

A litre of water for the roots? Thats amazing! How does that work that the roots actually 'pull' the water?

[ChloroPhil]

The plants suck up water through the roots to feed. It's a slow process, but a large healthy root system can move a lot of water.