Recirculating Aquaculture

[Eddie]

Hey All,

I found this article interesting and thought I'd share it. I like the part about feeding fish every 30 minutes.

http://www.pir.sa.gov.au/__data/asse.../recircmgt.pdf

Eddie

[Dkarc@Aol.com]

That is a pretty good overall paper on recirc systems. Good find.

-Ryan

[Chad Hughes]

Eddie,

Great paper! I'm sort of suprised that they did not site the benefits of plant beds incorporated in their recirc systems. Plant beds complete the nitrification process eliminating nitrate trough uptake.

Anyway, I also say that they mentioned the Ph levels and impact on biological filters. Low Ph is not deadly to biological filters, it just makes they far less efficient.

Good find my friend! It's a great article for those new to the hobby!

Best wishes!

[Dkarc@Aol.com]

Eddie,

Great paper! I'm sort of suprised that they did not site the benefits of plant beds incorporated in their recirc systems. Plant beds complete the nitrification process eliminating nitrate trough uptake.

Anyway, I also say that they mentioned the Ph levels and impact on biological filters. Low Ph is not deadly to biological filters, it just makes they far less efficient.

Good find my friend! It's a great article for those new to the hobby!

Best wishes!

The use of plants on large scale recirc systems is not practical (cost and space wise), which is where that paper is aimed at. When I say large scale, im talking 6 digit figures or more. Most farmers who use semi-intensive (and even intensive+) typically dont worry about nitrates to any appreciable level. Nitrates in those systems are typically 200-500+. I have seen some systems where the nitrates are into the thousands. Fish are not affected at all, but then again it depends on the fish species being cultured (ornamental vs food fish). There are a few farms out there that double crop with the water they use....grow fish, and use the same water for hydroponics (basil, lettuce, etc).

I agree though, it would be nice to develop a practical method to use plants on a large scale recirc system to control nitrates to some extent. Those farms that do use a complete nitrification cycle utilize anaerobic/anoxic filters and feed the filters with a simple carbon source (sugar, vodka, etc) and those bacteria convert nitrate into nitrogen gas and they degas the water to remove it effectively. From what I have seen, it is far more effective than using plants to do the same thing.

-Ryan

[kaceyo]

Hi Ryan,
I had heard that the water used by Stendker in Germany had nitrates in the neighborhood of 200+ppm. This was apparently not a big concern for him and I've always wondered if we make too much of keeping our nitrates so low. Or is it only in very large capacity water systems that high nitrates pose no problems for fish in general and discus in particular? What's your take on this?

Kacey

[Chad Hughes]

The use of plants on large scale recirc systems is not practical (cost and space wise), which is where that paper is aimed at. When I say large scale, im talking 6 digit figures or more. Most farmers who use semi-intensive (and even intensive+) typically dont worry about nitrates to any appreciable level. Nitrates in those systems are typically 200-500+. I have seen some systems where the nitrates are into the thousands. Fish are not affected at all, but then again it depends on the fish species being cultured (ornamental vs food fish). There are a few farms out there that double crop with the water they use....grow fish, and use the same water for hydroponics (basil, lettuce, etc).

I agree though, it would be nice to develop a practical method to use plants on a large scale recirc system to control nitrates to some extent. Those farms that do use a complete nitrification cycle utilize anaerobic/anoxic filters and feed the filters with a simple carbon source (sugar, vodka, etc) and those bacteria convert nitrate into nitrogen gas and they degas the water to remove it effectively. From what I have seen, it is far more effective than using plants to do the same thing.

-Ryan

Yes, I guess that would require some realestate! LOL!

Hi Ryan,
I had heard that the water used by Stendker in Germany had nitrates in the neighborhood of 200+ppm. This was apparently not a big concern for him and I've always wondered if we make too much of keeping our nitrates so low. Or is it only in very large capacity water systems that high nitrates pose no problems for fish in general and discus in particular? What's your take on this?

Kacey

Wow! That is interesting. Where did you read that?

[kaceyo]

Hey Chad,
It was either here or DAAH years ago, from someone that had visited the Stendker facility. I've heard this from others also, about various large scale breeding outfits.

Kacey

[Chad Hughes]

Hey Chad,
It was either here or DAAH years ago, from someone that had visited the Stendker facility. I've heard this from others also, about various large scale breeding outfits.

Kacey

Kacey,

I've heard that about commercial breeding of say trout, but never discus. You know how discus communities are. ZERO everything. I've gotten very good at eliminating nitrates. I wonder why their nitrates were so high?

[Eddie]

Hi Ryan,
I had heard that the water used by Stendker in Germany had nitrates in the neighborhood of 200+ppm. This was apparently not a big concern for him and I've always wondered if we make too much of keeping our nitrates so low. Or is it only in very large capacity water systems that high nitrates pose no problems for fish in general and discus in particular? What's your take on this?

Kacey

That is very interesting Kacey. Something to think about.

Eddie

[Dkarc@Aol.com]

Hi Ryan,
I had heard that the water used by Stendker in Germany had nitrates in the neighborhood of 200+ppm. This was apparently not a big concern for him and I've always wondered if we make too much of keeping our nitrates so low. Or is it only in very large capacity water systems that high nitrates pose no problems for fish in general and discus in particular? What's your take on this?

Kacey

Well for the Stendker facility and their nitrates, I have my own theories/opinions regarding that issue (breeding, raising, etc). But for reason why it works for them....a lot of it has to do with the general system stability. A lot of it has to do with stocking densities. High stocking densities like Stendker facility creates a lot of competition within the tank, making them eat very well. Discus are a schooling fish, but when put into an extreme like that they go into overdrive basically. Even with a high nitrate level in the system, if that is all they have been exposed to all their life then that is how they adapt....making them very hardy indeed.

Personally, I think the main reason why hobbyists cannot do that in their own tank is because by the time the nitrates reach such a level, the general water quality has gone down the toilet. In a large scale recirc system, it is a constant management nightmare. But just the sheer volume is what saves you most of the time. In a hobbyists tank, you would be micro managing the water quality (not just NH3/NH4+, NO2, NO3..) like oxygen levels, flow rates, biofilter retention times, solids removal, temp, alkalinity, chloride and a few more. It is an eco system and you must monitor and control all aspects of it to achieve the desired results. Stendker can do it so well because he has well managed systems. Not to say that everyone on here doesnt maintain their tank(s) well, but you have to question yourself how well it is managed if you have to do such large water changes all the time (not saying that I am perfect either...it is a constantly evolving art form). My thoughts on that though are due to the inefficiency of design/maintenance of modern aquarium filtration. That is an entirely other subjectfor another time.

It would be interesting though to find out what a discus' LC/50 is just to see how much they really could take when they're in a well managed system.

-Ryan

[kaceyo]

Following LC 50 testing is getting well beyond my aqua-abilities, lol. But feel free to explain if you have the inclination.
It makes sense though that a large capacity system that depends more on efficiant filtration and less on high % wc's would allow for much higher nitrate levels.
Thanks,

Kacey

[Dkarc@Aol.com]

Following LC 50 testing is getting well beyond my aqua-abilities, lol. But feel free to explain if you have the inclination.
It makes sense though that a large capacity system that depends more on efficiant filtration and less on high % wc's would allow for much higher nitrate levels.
Thanks,

Kacey

LC 50 means Lethal Concentration with a 50% fish kill @ "x" concentration ("x" being nitrate level in this case). There are published LC/50 charts out there for majority of the popular food fish (and shrimp)....it is a good indicator of how hearty a certain species really is and how tolerant of less-than-ideal water quality it is. Shrimp, from what I remember arent really affected by nitrate in their water. I think they tested them well into the 2,000++ range with little to no effect!!

-Ryan

[kaceyo]

Thanks Ryan. That's simple enough for even me to understand.

Kacey