Designing the Ultimate Filtration System

[RoadWarrior]

Thanks. Interesting stuff. I would say, though, that there are koi ponds as large or larger than 10,000 gallons in Japan and elsewhere being run very efficiently, with outstanding water quality, with what I believe to be less than 1,000 gallons of bio media. I could be wrong about that, but I don't believe so.

So, what is nature's secret to bio filtration without water changes? We can say it's primarily due to a far lower bioload, but have you seen some of the conditions in which healthy fish exist? Have you seen a shallow hippo pond, loaded with hippos, hippo dung and urine, with an underwater camera showing dozens of big, healthy fish swimming around? Surely that's not an environment with toxic levels of DOCs, ammonia, nitrite, nitrate or anything else. If it were, we'd see evidence of stress -- bacterial infections, fin and tail rot, etc. Yet the fish are in apparently perfect health.

Something is processing that bioload efficiently and thoroughly enough for healthy aquatic life to exist there, and without water changes.

I still see the holy grail of filtration as a system in which only evaporated water needs to be replaced (perhaps with trace elements added) in order for pristine water quality to be maintained -- a system with water replacement but not water change. To me, it's just a matter of time until such a system is a reality. I'm not saying it will happen tomorrow, but it will happen eventually with technological advancement.

I do also agree with those in this thread who've pointed out that the price of reducing water change frequency and volume may have too high a price in my current design. The juice may not justify the squeeze, so to speak.

[johnptc]

I still see the holy grail of filtration as a system in which only evaporated water needs to be replaced (perhaps with trace elements added) in order for pristine water quality to be maintained -- a system with water replacement but not water change. To me, it's just a matter of time until such a system is a reality. I'm not saying it will happen tomorrow, but it will happen eventually with technological advancement.

that is what i am striving for.....but the big koi ponds dont feed 10 pounds of dead fish a day..........i believe this would be a challenge for a bakki shower.........not that i didnt consider it before building my carbon nitrate filter.

i have added activated carbon to remove doc's.

the carbon fed denitrifing filter should restore alkalinity removed by the nitrification process......so far pH and alkalinity are holding stable and the nitrates are about 10 ppm much lower than i ever achieved with 24/7 water changes

[cvermeulen]

I read the koi article cited somewhere, claiming a regular trickle filter with bio balls and no other modifications removed nitrates. I find it pretty hard to believe... JohnPTC, I wonder if you tried running your carbon fed filter for a few days without the carbon supplement?? it might be a real eye opener for all of us if it worked without the chemical additive.

Another thing I'm thinking, is that the denitrifying cycle is the exact reverse of the nitrifying cycle... with different bacteria doing each job. So you get ammonnia from the fish, nitrite from your bacteria, nitrate from your other bacteria, then it goes into your denitrifier, and it converts nitrate to nitrite, and nitrite to ammonia, then ammonia to N2, and some other by products, depending on the type of denitrifier. This would be why if you get the dosing wrong you can wind up putting nitrites or ammonia back into the tank. If you are running a properly balanced system... shouldn't your ammonia rich water go FIRST into your anaerobic filter, so the bacteria there can convert the majority of the ammonia directly? The only problem with this that i can think of is the relatively slow response time due to the slow filter turnover rate. Thoughts?

[RoadWarrior]

that is what i am striving for.....but the big koi ponds dont feed 10 pounds of dead fish a day..........i believe this would be a challenge for a bakki shower.........not that i didnt consider it before building my carbon nitrate filter.

i have added activated carbon to remove doc's.

the carbon fed denitrifing filter should restore alkalinity removed by the nitrification process......so far pH and alkalinity are holding stable and the nitrates are about 10 ppm much lower than i ever achieved with 24/7 water changes

Since I'm not a koi farmer, I really don't know what the average food weight is per day for large koi, but it has to be substantial. No, they're not fed fish, but they are fed protein-rich pellets, prawns and other meaty foods that have to be broken down by bio filtration, and they create a lot of waste.

Unfortunately, I just don't have enough data to cite any reliable numbers.

[RoadWarrior]

Also, not sure how many here have heard of this before, and I only read about it for the first time two weeks ago, but many koi and goldfish hobbyists actually don't use ANY biological filtration.

Instead, they use what they call "green water," which is specially cultivated water so rich in algae that it's actually green. The waterborne algae feast on the ammonia, nitrite and nitrate, and also provide tremendous oxygen to the water.

In green water systems, there's no bio filtration -- only water changes replacing old green water with new green water.

This system apparently works very well, but has a huge downside, which is that visibility is greatly compromised. Not exactly what you want in an indoor fish tank that's there to be viewed, but still interesting nonetheless.

[johnptc]

Since I'm not a koi farmer, I really don't know what the average food weight is per day for large koi, but it has to be substantial. No, they're not fed fish, but they are fed protein-rich pellets, prawns and other meaty foods that have to be broken down by bio filtration, and they create a lot of waste.

Unfortunately, I just don't have enough data to cite any reliable numbers.

me either....... i thought they ate more veggies but maybe not.........also at cooler temps they should consume less food.... just a guess.

[RoadWarrior]

me either....... i thought they ate more veggies but maybe not.........also at cooler temps they should consume less food.... just a guess.

Yeah, that's a valid point about lower temperatures lowering metabolism and food requirements.

Koi are omnivores, so they're eating a balanced diet. However, veggies also create waste. Have you ever smelled broccoli that's been sitting in the fridge for too long? I'm not sure there's a worse smell.

[frasertheking]

Also, not sure how many here have heard of this before, and I only read about it for the first time two weeks ago, but many koi and goldfish hobbyists actually don't use ANY biological filtration.

Instead, they use what they call "green water," which is specially cultivated water so rich in algae that it's actually green. The waterborne algae feast on the ammonia, nitrite and nitrate, and also provide tremendous oxygen to the water.

In green water systems, there's no bio filtration -- only water changes replacing old green water with new green water.

This system apparently works very well, but has a huge downside, which is that visibility is greatly compromised. Not exactly what you want in an indoor fish tank that's there to be viewed, but still interesting nonetheless.

would this not cause a lack of oxygen at night ?

[RoadWarrior]

would this not cause a lack of oxygen at night ?

I don't know enough about green water to know how they solve that problem, because, as you indicated, at night, the waterborne algae will consume oxygen and release CO2 into the water.

Here's what I could find on one of the forums about it:

That's why it's very important to regulate the degree of green-ness with regular water changes. If the water becomes dark green, there's an over concentration of algae, which could be a problem both for O2 and ph levles. By keeping the water bright green, there should be no problems at all. Around here, it ends up being weekly water changes of 80-90%. With the green water method you can raise healthier, more brightly colored fish. Are you currently keeping green water?

Also, I've read that O2 and CO2 level are independent of each other... so it's possible for a pond to have high 02 and high CO2 levels. By maintaining good circulation with an air stone all night, you can keep the tank well oxygenated, even though the algae is absorbing O2 and creating CO2.


Also, for those with an interest in Bakki Showers and especially the DIY variety, the attached thread is really interesting and has a link to a thread on a DIY Bakki Shower that someone at arowanaclub.com did.

http://www.rafflesgold.com/forums/in...showtopic=3895

[tbonewarrior]

Just a thought... if you were to add fertilizers for the desirable in-tank plants, wouldn't the reeds just eat those up too? Just wanted to nitpick here...