Designing the Ultimate Filtration System

**Miguel** · 04-15-2008, 6:10 PM

great thread, you engineers, you! hehehe!

**RoadWarrior** · 04-15-2008, 6:29 PM

Originally Posted by tbonewarrior;1709234;

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...

I can only speculate, as my original post was not based on personal experience. It was theoretical. Experiments would have to be conducted to answer that question.

However, in a natural setting, reeds and other shoreline plants co-exist successfully with other aquatic plants and don't starve them out.

**Oscarboyz** · 04-15-2008, 8:03 PM

I think your idea is very nice welcome to MFK

**RBE17** · 04-16-2008, 6:56 AM

Originally Posted by spiff;1708773;

It makes me wonder how useful an airstone might be in a sump if you didn't already have an aerated system dumping into it...

Probably very useful. A lot of those pond filters rely on the agitation of air to create the moving bed. I think smaller, floating media would be needed in the sump.

**RBE17** · 04-16-2008, 7:32 AM

Originally Posted by RoadWarrior;1709124;

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.

I think a lot of that depends on the type of koi being raised. A farmer and a shower trying to raise a grand champion might feed very heavily.

Originally Posted by RoadWarrior;1709136;

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.

I have never heard that before. All of the koi and ponding forums I've read have never mentioned it. It seems a little wacky to me.

Originally Posted by johnptc;1709141;

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

A lot of people bring their koi inside for the winter and keep them in a basement tank. These are koi that go from a pond to 50%-90% less in volume. Plus they are being kept at decent temps in the basement so the need for regular feedings is there. The bio load for the basement tanks is large.

Originally Posted by RoadWarrior;1709190;

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

That gentleman, Dick Benbow, is an authority on koi. I believe he's written some books concerning them.

Also, did anyone notice how he says he breaks a piece of BH media open each year and smells it?

**spiff** · 04-16-2008, 8:37 AM

I tested my system last night, and it does seem to be removing nitrates though this difference is barely detectable. I did four tests with a dedicated nitrate test, two out of the tank and two from the return. I kept all the result solutions to do an immediate comparison... and apparently an ordinary gravity system with out any special media or aeration going on removes nitrates too.
Although, admittedly, the color difference on the samples were barely detectable, but I got a second opinion on someone and we both think was a difference. How much this represented in PPM is unknown though.

I guess the next test would be to see if this gets more effective with the more nitrates in the water. I ever only have a max of 30-40PPM, so natural removal of nitrates might be not so effective. I'm thinking that if you let the system build up nitrates, to say 80ppm or more, the filter might at some point stabilize and keep a steady nitrate level. I'm just speculating here.
My filter has a capcity of about 430gal for a 2000gal tank...(two stacks of 3 56gal rubbermaids forming waterfall system both dumping into a 90gal sump- all pillow stuffing and pot scrubbies), so it represents a high ratio of filtering for the overall volume.

**Dr Joe** · 04-16-2008, 9:02 AM

Originally Posted by spiff;1711081;

I tested my system last night, and it does seem to be removing nitrates though this difference is barely detectable. I did four tests with a dedicated nitrate test, two out of the tank and two from the return. I kept all the result solutions to do an immediate comparison... and apparently an ordinary gravity system with out any special media or aeration going on removes nitrates too.
Although, admittedly, the color difference on the samples were barely detectable, but I got a second opinion on someone and we both think was a difference. How much this represented in PPM is unknown though.

I guess the next test would be to see if this gets more effective with the more nitrates in the water. I ever only have a max of 30-40PPM, so natural removal of nitrates might be not so effective. I'm thinking that if you let the system build up nitrates, to say 80ppm or more, the filter might at some point stabilize and keep a steady nitrate level. I'm just speculating here.
My filter has a capcity of about 430gal for a 2000gal tank...(two stacks of 3 56gal rubbermaids forming waterfall system both dumping into a 90gal sump- all pillow stuffing and pot scrubbies), so it represents a high ratio of filtering for the overall volume.

Can you post pix of your filter?

**RoadWarrior** · 04-16-2008, 9:29 AM

Originally Posted by RBE17;1711000;

I have never heard that before. All of the koi and ponding forums I've read have never mentioned it. It seems a little wacky to me.

I agree that green water is a little wacky. People who use this method of filtration swear by it and cite two advantages of the system:

1) Complete removal of ammonia, nitrite and specifically nitrate
2) More vibrant color in their fish

As far as point #1 is concerned, there are other ways to address nitrates, and as for point #2, I'm convinced that this phenomenon has much more to do with the fact that the fish are feasting on the algae in the water, which is loaded with certain vitamins and minerals that serve to enhance their color.

However, I believe that you could mimic that effect through certain vitamin supplements, or by just supplementing their diet with a similar algae product.

**cvermeulen** · 04-16-2008, 9:54 AM

Originally Posted by spiff;1711081;

I tested my system last night, and it does seem to be removing nitrates though this difference is barely detectable. I did four tests with a dedicated nitrate test, two out of the tank and two from the return. I kept all the result solutions to do an immediate comparison... and apparently an ordinary gravity system with out any special media or aeration going on removes nitrates too.
Although, admittedly, the color difference on the samples were barely detectable, but I got a second opinion on someone and we both think was a difference. How much this represented in PPM is unknown though.

I guess the next test would be to see if this gets more effective with the more nitrates in the water. I ever only have a max of 30-40PPM, so natural removal of nitrates might be not so effective. I'm thinking that if you let the system build up nitrates, to say 80ppm or more, the filter might at some point stabilize and keep a steady nitrate level. I'm just speculating here.
My filter has a capcity of about 430gal for a 2000gal tank...(two stacks of 3 56gal rubbermaids forming waterfall system both dumping into a 90gal sump- all pillow stuffing and pot scrubbies), so it represents a high ratio of filtering for the overall volume.

I lost the link, but one of the koi forum discussions cited either in this thread, or several of the other MFK nitrate threads that have been mentioned in this thread contains many claims from koi keepers, stating that they have <10ppm nitrates just by switching from a standard wet biofilter to a trickle filter. The testament of many is a convincing thing, but I still find it a bit of an outlandish claim without any explanation of HOW this happens. So far the mechanisms for nitrate removal can be summarized as:

1) Plants (Duh)
2) Anoxic sulfur based bacteria produce N2 and Hydrogen Sulfate (H20+2xNO3+S=N2+H2SO4). The sulfer source being sulfur salts from decomposed food, dechlorinators, etc. usually, although it's doubtful the general bio load produces enough sulfur to deal with the associated amount of nitrate.)
3) Anoxic Carbon based bacteria produce N2 and CO2 (2xNO3+3xC=N2+3CO2). This requires bioavailable carbon in the form of alcohol or sugar, or the micro g C product JohnPTC is using.

Both known forms of microbial denitrification require a food source, and anoxic conditions... soooo it remains to be explained how this happens in an aerated filter. Method 2 seems to happen without the addition of sulfur in things like RDSBs and coil dinitrators, so maybe method 2 can actually find enough sulfur from the same sources as the nitrate to eliminate the nitrate... it just seems like you're getting something for free here though that shouldn't really work. Plants have an outside energy source to process the nitrate, Carbon based microbes use the energy stored in the alcohol or sugar... where do the sulfur based bacteria get their energy, if nothing else gets added to the water? And how can this process possibly take place in a heavily oxygenated environment (with the exception maybe of the biohome capilliary media).???

**spiff** · 04-16-2008, 9:55 AM

No, sorry, i still don't have a digital camera. I do have a few pics of the construction of the tank when I borrowed a blackberry... but none of the filter. But the setup is as simple as you can imagine: using a siphon overflow so I didn't have deal with bulkheads (would be problem since I used 6x6's), using 3in PVC dumping into to two stack of 56 gallon rubbermaids above a 90 gallon acrylic sump.