Aquarium science...

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pbecot01

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Dec 27, 2004
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This may be an off the wall question.

In marine setups, with a deep-sand bed, sand-critters, and live rock the nitrogen cycle gets rid of ammonia and cleans up detritus and the like from the tank.

So my question is, why doesn't this work in freshwater aquariums? Do the bacteria to finish the cycle require saltwater? And aren't there little worms and ameobas and the like living in rivers that we could populate our freshwater sand-beds with to help clean the bottom?

I actually enjoy doing my weekly water changes, but if the fish could have a cleaner environment in between, I would certainly be all for it!

Thanks anyone who has any idea why this is :)
 
It actually does work in freshwater.
The bacteria - Nitrosomonas and Nitrobacter - require surface area and oxygen. Usually filter media provides for plenty of bacteria space. In planted tanks, I believe, plant surfaces also provide this space.

In saltwater tanks with liverock, you have lots of surface area in the tank. Also, (and it's been a while since I've kept saltwater fish) you have giant sumps with bioballs or those penguin wheelie gizmos, and protein skimmers and all sorts of hoo haas and tchochkies.

You can have freshwater invertebrates also, if you like. I have a couple of ghost shrimp. Lots of folks have those amano shimp. If you don't have plants your list can grow even bigger. Often in freshwater tanks, if there is a little unidentified critter on the glass or in the substrate, people freak out and pour in chemicals to kill them. These critters will all eat detritus.

I remember the book I used to read to my son - "everybody eats, so everyone poops". The inverts in both fresh and saltwater tanks create their own detritus. It can only be avoided by avoiding organisms. Aquaria are closed systems so water changes will always be required unless we can capture evaporated water, never feed, and have only a teeny bioload.
 
Doesn’t your 75g planted tank (the plants) wisk away the nitrogen from the water column?

Aquatic arthrpod larvae are the FW equivalent to SW ‘critters”. There’s also FW amphipods and annelids, though not as large or colorful as some of their SW brethren.


Tom
 
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I usually run about 10-20 nitrates. I believe the bacteria that actually eliminate the nitrates are anareobic... I am hardly a scientist, and thourough discussions of matters can be hard to find.

The plants get SOME of the nitrates, and will probably get more when I install CO2 and start fertilizing them properly (am away from home for a couple months and the wife complains enough about just doing the water changes and feedings lol)

When I said "cleans up ammonia" I meant nitrates. I couldn't keep fish for very long with an ammonia problem ;)

If you could help me out... what are arthrpod larvae, amphipods, and annelids?
 
This is an interesting topic, I have studied this quite a lot. You can do the all of the things that the saltwater gang are doing, it just that the methods can vary a little bit. As in salt water live sand beds, plenum's, deep sand bed and using plants, whether it be algae or higher plants to reduce nutrients in the water colum. There are plenty of these critters in freshwater to do the job of detritus removing and these are called detrivoes. Arthropod larvae are infact insect larvae, they can be usefull as well. Most of the time we have these crtters in our tank, we just don't know it, also with a big fish populations over-predation can be a problem. But there are many ways to set your tank up to reduce the levels of nutrients in your tank, I suggest your do some more reading, or if you know what method you want to use , I am sure one of us will be able to help you here.
 
okay... any helpful links? :)
 
Try here ,and put in words like deep sand bed ect. Goodluck ;)
 
pbecot01 said:
okay... any helpful links? :)
Click to expand...

Arthropod larvae (probably more at 'insect larvae'):

Arthropod = Any representative of the phylum Arthropoda (encompassing insects, arachnids [as spiders, mites, and scorpions], myriapods [millipedes and centipedes], and crustaceans), characterized by a chitinous exoskeleton; a bilaterally-symmetrical, segmented body; and paired, jointed legs.

Larva (plural larvae) = The immature stage of an organism's life

Amphipod = Any representative of the crustacean order Amphipoda

Annelid = Any representative of the phylum Annelida, including earthworms and leeches
 
Plenums work just fine in FW without being concerned with diggers. I have not tried FW DSB, so can't say there (I do not trust deep anaerobic conditions in my tanks, no thank you). The denitrification bacteria are anaerobic, not aerobic, but not as deeply so as the bugs with generate H2S and methane,so to me the DSB is unnecessary overkill.

In FW you can do higher plants as mineral (including ammonia & nitrate) sequestration devices. You remove excess growth and incorporated minerals go with the package.
 
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