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10 Gallon with Anoxic Filtration


Gideyon
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I've started a few threads to get information and now I'm finally starting to work on it. However, I forgot to take pictures of the first day.  I wanted to start this journal to document the process for my own benefit, but maybe others can as well. 

This stems from a desire to experiment with anoxic filtration, using a slow moving plenum as described by Dr Novak. 

A lot of people criticize his work without actually trying it. But I want to try it. I don't understand the science of it all, but I do understand anaerobic conditions is important.  And if all goes well, a true nitrogen cycle can take place when nitrates are not just used by plants, but bacteria consumes it. 

If this is successful, my next experiment will be in a 20 gallon with shell dwellers. No plants, obviously.  So before I mess with higher priced fish that are sensitive, I'll start with hardy fish. 

This 10 gallon will be planted with low tech plants. I don't intend to use ferts or CO2. Just lights 5 hours a day. 

The parts/pieces I'll be using:

- 10 gallon aqueon tank that's about 5 years old

- Safe T Sorb as a substrate 

- laterite 

- plants from the co-op: so far leaning toward wisteria, dwarf sag, and crypt lutea. 

- co-op USB powered air pump with tubes 

- air stone 

- plen plax UGF

- fine mesh filter media bags

- whisper 10 HOB with coarse sponge and ceramics 

- Dr Tim's for cycling. 

- fish; I'm leaning toward white clouds, but considering endler live bearers to satisfy my son's desire for color. 

 

Day 1: sift through safe t sorb.   Pictures wouldn't be exciting anyway. 

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It should be interesting.  I am afraid that I, too, lack an understanding of the science/chemistry involved. I have seen "anoxic" used to describe a lack of oxygen and also to describe a low-oxygen condition. In either case, it has never been clear to me how to expose aquarium water, which should not be anoxic by any definition, to an anoxic location where nitrates are removed. If aquarium water is flowing through the location, it would seem that the location cannot remain anoxic. If aquarium water is not flowing through it, how can nitrates be removed from the aquarium water?

This may not be a legitimate problem, but in my head it is a roadblock to considering anoxic removal of nitrates.

Good luck!

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Day 2 (I didn't do anything over the weekend):  rinse the substrate and get the UGF ready. 

This is the first time I'm rinsing a non-gravel substrate. That's no joke.  No telling how many gallons of water I used.  I still didn't get the water clear but clear enough. 

The UGF... If any of you ever decide to work with Plen Plax, use strong scissors.  The way of the directions will leave you frustrated.

Because I was using a non-gravel substrate, I was concerned of smaller particles getting through. So I cut up some very cheap nylon filter media bags and laid them on top.  It looks rather clumsy but I'm just being overly cautious. 

I also cut the uptake tube. It's 4" about. Novak recommended it be right above the substrate, but this will be an inch higher. 

I also noticed that with the UGF, the intake of the HOB is less than or very close to 3" from the raised floor.   This will be a problem.  I may need to make it shallower on that side.  But I was also hoping to put wisteria on that corner.   We'll see. 

I only get about an hour a day to work on this. I didn't get to adding the substrate and water yet.  Hopefully tomorrow... 

 

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On 8/9/2021 at 2:43 PM, Gideyon said:

I also noticed that with the UGF, the intake of the HOB is less than or very close to 3" from the raised floor.   This will be a problem.  I may need to make it shallower on that side. 

I wonder if you can cut the intake tube to be shorter. As in, pull off the sponge or grid-like attachment that's stuck on the bottom of the tube, saw some of the tube off, then stick the sponge or grid back onto the spot you sawed. Maybe. 

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I don't know this anoxic filtration system described by Dr. Novak but these systems are actually very well understood in the sewage treatment industry where they need to optimize the whole process to keep costs down. You can look at what they've learnt to understand what you need to make it work efficiently. E.g. here's a somewhat digestible form of it https://www.meatinstitute.org/index.php?ht=a/GetDocumentAction/i/48700

If you look at the problems section, there are a couple of points there that I think would make it difficult in a home aquarium:

  1. Low recycle rate - to be effective the whole system needs to be a closed where the water is constantly recirculated (between the anoxic chamber and the preparation chambers). To get to 80% nitrate -> nitrogen gas conversion rate, they need a 400% recirculation rate. Keep in mind this is commercially optimized equipment and system so for home aquariums, you'll likely have to seriously up the recirculation % to make up for it. Even if you got anywhere near that, you're still not getting all the nitrates out.
  2. Oxygen carryover from aerated zone - this is the concern that @HH Morant has. Pumping water in brings oxygenated water. To remove that, they add an organic food source, looks like typically an alcohol, so that heterotrophic bacteria can consume it and use up the oxygen in the normal respiration process. It takes time for the bacteria to consume the oxygen which is why they have a couple of chambers before to allow that to happen.

It'll be interesting to see what happens but looking at the numbers this industry is doing, I feel any home system would just be insanely inefficient, leaving a bunch of nitrates you still have to deal with. Or any home system that can do it semi-efficiently would be insanely complex to build and maintain.

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On 8/9/2021 at 5:32 PM, AlgaeIsYum said:

I don't know this anoxic filtration system described by Dr. Novak but these systems are actually very well understood in the sewage treatment industry where they need to optimize the whole process to keep costs down. You can look at what they've learnt to understand what you need to make it work efficiently. E.g. here's a somewhat digestible form of it https://www.meatinstitute.org/index.php?ht=a/GetDocumentAction/i/48700

If you look at the problems section, there are a couple of points there that I think would make it difficult in a home aquarium:

  1. Low recycle rate - to be effective the whole system needs to be a closed where the water is constantly recirculated (between the anoxic chamber and the preparation chambers). To get to 80% nitrate -> nitrogen gas conversion rate, they need a 400% recirculation rate. Keep in mind this is commercially optimized equipment and system so for home aquariums, you'll likely have to seriously up the recirculation % to make up for it. Even if you got anywhere near that, you're still not getting all the nitrates out.
  2. Oxygen carryover from aerated zone - this is the concern that @HH Morant has. Pumping water in brings oxygenated water. To remove that, they add an organic food source, looks like typically an alcohol, so that heterotrophic bacteria can consume it and use up the oxygen in the normal respiration process. It takes time for the bacteria to consume the oxygen which is why they have a couple of chambers before to allow that to happen.

It'll be interesting to see what happens but looking at the numbers this industry is doing, I feel any home system would just be insanely inefficient, leaving a bunch of nitrates you still have to deal with. Or any home system that can do it semi-efficiently would be insanely complex to build and maintain.

Thanks for the link.  I'll have to read it more closely when I get a chance. But you're right, that is the simplest way I've seen explaining it.   

I don't know if this will answer your questions or not....

The substrate is a baked clay, and will have laterite (iron source) mixed in on the lower inch of it. That combination helps with nitrification from what I understand. Again, I don't get the science of it, but the clay provides some kind of electrical charge that helps with the filtering. 

The air for the airlift will only be on about 16 hours a day.  And even when it is on, it'll be at a low rate.  The airlift tube is only on the right side.  The water by the right plate will move faster than the left.  I'm thinking the left side will have more of the anaerobic conditions (low oxygen) than the right.   It'll have no movement at night.   

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On 8/9/2021 at 7:03 PM, Gideyon said:

Thanks for the link.  I'll have to read it more closely when I get a chance. But you're right, that is the simplest way I've seen explaining it.   

I don't know if this will answer your questions or not....

The substrate is a baked clay, and will have laterite (iron source) mixed in on the lower inch of it. That combination helps with nitrification from what I understand. Again, I don't get the science of it, but the clay provides some kind of electrical charge that helps with the filtering. 

The air for the airlift will only be on about 16 hours a day.  And even when it is on, it'll be at a low rate.  The airlift tube is only on the right side.  The water by the right plate will move faster than the left.  I'm thinking the left side will have more of the anaerobic conditions (low oxygen) than the right.   It'll have no movement at night.   

What is the reasoning for running the airlift for only 16 hours per day? I must have missed that point.

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On 8/9/2021 at 7:09 PM, Scott P. said:

What is the reasoning for running the airlift for only 16 hours per day? I must have missed that point.

One tremendous weakness in Novak's videos is that they're incredibly long and occasionally he'll add a different thing about anoxic filtration.    So I can't find the video in which he suggested this, nor why. It wasn't a requirement.  I took a lot of mental notes but the why to this I can't remember.  I have this vague memory of him saying it decreases oxygenation even more. 

 

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On 8/9/2021 at 7:57 PM, Gideyon said:

One tremendous weakness in Novak's videos is that they're incredibly long and occasionally he'll add a different thing about anoxic filtration.    So I can't find the video in which he suggested this, nor why. It wasn't a requirement.  I took a lot of mental notes but the why to this I can't remember.  I have this vague memory of him saying it decreases oxygenation even more. 

 

Yeah Dr Novak does have a way of rambling on. His videos could be shorter.

He does say that this system can take a while to get to its full potential. Just seems to me by cutting off the flow would be counter productive as far as growing bacteria goes.

I most certainly could be wrong but I can't remember him saying anything about it.

If you do happen to find it please let me know as I must have missed it.

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On 8/9/2021 at 9:53 PM, Scott P. said:

Yeah Dr Novak does have a way of rambling on. His videos could be shorter.

He does say that this system can take a while to get to its full potential. Just seems to me by cutting off the flow would be counter productive as far as growing bacteria goes.

I most certainly could be wrong but I can't remember him saying anything about it.

If you do happen to find it please let me know as I must have missed it.

 

I didn't find it but he did say in a video I skimmed through that if the plates had enough holes/slits throughout, you don't need an airlift. Because water would naturally move slowly in and out of the substrate. But some UGFs aren't like that.  Like mine, for example.  It's harder for water to go in and out without the airlift.  

In addition, while it wasn't the same video, he did say in this the time to turn it off is when you're adding co2. 

So I'll just keep it on for now until I find that few minutes in the midst of hundreds of minutes of videos. 

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Day 3:  put the substrate in.  After a half inch or so, added laterite. Then the rest. 

I decided to crush a handful of ceramic rings to place under the UGF, as they wouldn't fit as a whole piece. 

PXL_20210810_152800416.jpg.5ee81824bb70378c1f2634feeae91830.jpg

I wasn't sure how much laterite to put, so I sprinkled it over the layer.  Then put the rest of the substrate in. 

PXL_20210810_154605868.jpg.05bb228873d454ae66bdf2c697781417.jpgPXL_20210810_183753181.jpg.740772db6deb6eff379a7ae57c653af9.jpg

Filled it with water and it's the expected cloudiness.  I have the airpump and my HOB running.   Not sure if that'll help settle sediment or not. 

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Worry #1: my mechanism to deflect the water as I added it failed half way through.  A bit of a crater was formed but I'm not sure if it reached the laterite layer.  If it did, that attributes to some of the cloudiness, and this whole experiment fails. 

Worry #2:  how do I know the UGF lift tube is pumping out water?  

Worry #3: what are those bubbles? 

 

After the dust settles..... 

I'm considering starting the cycle before plants, so I can get a true reading on nitrates.  Expecting to be unable to do anything significant with the tank for a couple of months so I figure it's a good time to do the cycling.  Any thoughts?  Otherwise I need to get the plants this week somehow. 

 

Update:  the dust is settling.    There are 2 small dragon stones.  I had two larger ones but it was too big. With the high substrate taking 2.5 gallons, I didn't want to lose more swimming space for the occupants. 

PXL_20210810_215848306.jpg.a659f60d1501db8f6aac66cb989e4157.jpg

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I'm sure now that the laterite exploded. I see red dust in the sponge and settled on the lift tube. 

Great........ 

I'm researching if this will be harmful for fish, because it is a powder.    But I'm planning on draining the tank, and gravel vac what I can.     Then do some digging to add the laterite again. 

I'll have to try another method of adding water via bucket.  Maybe lay some plastic on the surface, weighted down with the rocks.  I don't want to do the saucer method again.  The water lifted it for a brief moment and all went wrong after that. 

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I don't think you can draw any meaningful conclusions from this experiment unless you add no plants or livestock, do no water changes, only add distilled/RO water (to ensure you're not adding nitrates) and add a controlled amount of ammonia constantly. Plants will take up ammonia/nitrates, water changes will remove nitrates, having livestock means you need to feed them so you're adding variable amounts of nitrogen + the fish assimilate some of that, mulm builds up which locks nitrogen in solid form etc. With the whole system being that complex, it's pretty much impossible to attribute an effect to any one particular thing.

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On 8/11/2021 at 8:12 AM, AlgaeIsYum said:

I don't think you can draw any meaningful conclusions from this experiment unless you add no plants or livestock, do no water changes, only add distilled/RO water (to ensure you're not adding nitrates) and add a controlled amount of ammonia constantly. Plants will take up ammonia/nitrates, water changes will remove nitrates, having livestock means you need to feed them so you're adding variable amounts of nitrogen + the fish assimilate some of that, mulm builds up which locks nitrogen in solid form etc. With the whole system being that complex, it's pretty much impossible to attribute an effect to any one particular thing.

Great point.  After I fix this mess, I'll start the cycling without plants. 

The only reason for me to stop the experiment once ammonia is 0 is if my family insists I put in fish instead of looking at an unpopulated aquarium. 

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Day 4:  undo yesterday's disaster.

I finally got it fixed I hope.  Gravel vac'd as much water as I could.  Dug out a couple of inches or so.  I could see the laterite still there in some pockets where I originally put it. So I didn't add too much more.  

Refilled using a bigger and heavier plate.  It filled up better this time.  Now the cloudiness is less red. 

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I'm keeping the filters off while it settles so I don't get dust in the media.   I modified my HOB just as I did before. I won't add the polypad for this test.  Only after the tank is established. 

Also, the intake tube touches the substrate. I don't want it to pull water from the substrate, so I'll keep it off.  I'll have to figure out a way to put a pre-filter sponge where the tube would attach. 

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I see that foam again on the top. Not sure what it is. I wiped it up with a sponge.  

So now the plan is when this settles, I'll dechlorinate with Prime.  Take a baseline test of water parameters.   Then if time permits, add the ammonia up to 2ppm. 

I've never done a fishless cycle, so if I'm doing anything wrong during the process, please do tell.  

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Day 5: few more mods and baseline water test

 

I modified my uplift to something @tonyjulianodid with his. It's much better.

PXL_20210813_163507344_MP.jpg.6f3578682885927dac8289e8bbd9f681.jpg

I also used my old aqueon intake, cut off about an inch, and attached that with an intake sponge. 

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Then came the water test. Bad news... 

Something strange happened.  pH dropped to 6 (normally 7.2), and KH is 0.   There's also 0.5ppm total ammonia, and maybe 5ppm nitrate.   

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What on earth happened..... 

The substrate isn't known to do this. I don't think laterite would either.  I don't know if it was me using water out of my garden hose as opposed to indoor plumbing. 

I can't do a 100% water change without affecting the laterite layer.  But I'll try at least 75% and see if anything changes.   And use indoor plumbing. 

 

Update:

After a water change (down to substrate level), pH is back to normal, ammonia is a fraction above 0, but nitrates were still 5-10ppm. 

I'm going to wait a while to see if the pH decreases later. 

As for the nitrates.... It turns out my tap water has it.  

I'm not going to buy more things to get 0 nitrates. So assuming my pH is stable, I'm going to continue with the cycle. It's just that my baseline will be about 10ppm.

If pH drops again...... Plan b. 

Edited by Gideyon
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I had a similar deal happen when I set up safe t sorb as a substrate. The fish I put in there, cherry barbs, white clouds, bronze cories, really didn't mind the low pH. But then, those are not the most sensitive fish in the hobby. The snails were very unhappy in such a soft system. I ended up buffering my water with seachem alkaline buffer. Interestingly, as my kH normalized, my gH also dropped a bit. Unsure what happened there. Crushed coral would probably be a more natural source of gH and kH.

My 45 gal sailed like a breeze until a few months ago after a top off... I topped off the tank as usual, but then the tank clouded up later that day and I only had trouble after that. High levels of dissolved organic compounds (yellow frothy water) would keep coming, string and staghorn algae explosion, and untimely fish demise. Idk if it was chlorine in my tap (municipal city), bad dechlorinator, or the force of pouring water into the tank disrupting the balance I had going on. I get the feeling I didn't add enough declorinator as I think the city adds more chlorine in the summer when our reservoir warms up after spring. ¯\_(ツ)_/¯

 My other tanks are chugging along just fine though. I just evacuated my minnows, barbs, and cories into my nursery 10 gal. I'm redoing the 45 with the substrate at a 3-4 inch height (It was 7-8 inches in some places). Looking forward to getting more fish as well.

Glad to see your progress on the setup! 

 

Here's some photos of just before things started going downhill.IMG_20210721_164217352.jpg.24c4b61edf1268ed1a9c16d946e1848a.jpg

IMG_20210721_164208342.jpg.b4acf96d5ac7c7f611eae125146d1d16.jpgIMG_20210721_164154304_HDR.jpg.50b0660fccfa4a9d371bb668ac19c7b1.jpg

 

 

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