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edmolina

New Aquaponics System - Use of soil medium over hydroton with continuous flow

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Hello all,

I am about to start my 2nd aquaponics system (after a small proof of concept experiment a year ago). The system components are a rubbermaid 150 gal stock tank FT, two 3'x5'x14" deep, 100 gal hydroponic reservoirs as the GB's, radial flow filter, and sump/moving bio-filter. One GB is planned to contain only hydroton, while the other will have a soil mix (soil/vermiculite/compost) over a few inches of hydroton; both will be sub-surface, continuous flow.

Flow is as follows (all gravity except from sump to FT):

FT -> radial flow filter (also contains Matala filter) -> GB's -> sump/moving biofilter -> pumped to FT

I have two questions (and any other feedback is appreciated):

  1. How deep do I make the hydroton GB vs. how deep do I make the water height? Although I have read about going with a 6"/1.5" ratio, I already have the tank/material to make this 12"/4" (or something like that) and wonder if there is a benefit to going deeper, or if it is just a waste.
  2. Same question for the soil medium GB. I can't seem to find much on this, and have been intrigued ever since reading about the soil beds that Paul at Earthan has setup.

Regards,

Eddie

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The hydroton GB can be as low as 15cm although most people go deeper than that - it depends a bit on the plants you want in there and how much root room they need. You could probably stay shallow and stake or tie up tall plants that might fall over. The water should not get to the light - maybe 30mm from the top of the hydroton would be about as high as you want it getting - helps prevent algae growth as well as prevent your hydroton from floating at high tide.

Look up 'wicking bed' on the site for the soil version - if you have soil in there I doubt you will be wanting to feed the water back into the FT. A wicking bed would be a much better solution, I think.

Iam not sure why you have your return-to-FT going to the biofilter - you'd be feeding nitrates back into the FT when you really want them out in the GB. Also, if the GB is properly sized, you'd be starving the bacteria in the biofilter by sending only clean water in there.

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Thanks for the reply journey.

My concern with the water height is primarily with how low can I keep it and still get enough capillary action especially when the plants are small/seedlings.

I have read about wicking beds and plan to use them elsewhere in the garden, but had hoped to incorporate soil into the closed loop system borrowing from what I have read about Paul's work. It seems that the only issue would be tannins in the water. Maybe this is to ambitious at this point and I should stick with pure hydroton beds for now.

Regarding the bio- filter, I thought that any nitrates in the system would just flow, circulating through until used by the plants. Much of this design was modified based on what I have read on this site and in the manual. I believe the Queenslander is a similar layout, but maybe I misunderstand the arrangement.

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Ask Gary about the Queenslander system. I doubt you want nitrates flowing back into your FT. The idea is to have water as pure as feasible re-entering. Look up CHOP 2 systems - the problem there is the recirculation of impurities that should be getting cleared out before returning to the FT.

There is more than tannins at issue in soil beds; the chemicals found in soil are often lethal to fish and many of the extra nutrients required in soil are not good for an AP system. The design of AP is to allow the waste from the FT to grow your plants - wicking beds allow that system of nutrients to work in a non-AP system, but I don't know of anyone returning wicking bed water to the FT.

But I am relatively naive in all this - ask the more experienced.

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I am not planning F&D earthen bed, but rather a continuous flow bed where the water level is below the soil line. Geo textile would separate the hydroton from the soil and serve as a wick.

In this manner, there wouldn't be much leaching from the soil. The soil would be a mix, with only organic components. Does this change your perspective Gary? And Paul, is this more or less what you are doing, which seems to be working so well?

Also, 'new' in the title seems to be misleading. I mean a new system that I'm setting up, not a new approach.

Edited by edmolina (see edit history)

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As Journeyman said, "soil" is likely to contain substances that are not helpful to fish. Tannin is less of a problem - it's the volatile organic compounds that may be in the "soil" that are much more likely to be an issue.

The soil has never caused any issue. All the fish are still alive and thriving even after heavy rainfall.

Paul

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Anyone know how to include a larger version of the images that I post? I would like to include updates as I proceed, but the images that I am adding are showing up rather miniscule.

I started this thread as my first post because I am anxious to work out some final details before plumbing out and starting the system this Monday. Yet, I was remiss in introducing myself (although this likely belongs in a different section). I am a backyard sustainability enthusiast with emphasis on food production. To borrow from Gary's nomenclature, I would say that I am into Microponics and dabble in:

- hens for egg production, manure for the garden, bed prep after growing cover crop, and compost turning

- raised garden beds, which are covered by a hoop house over the winter, and am considering converting to wicking beds

- indoor aquaponics setup (just starting a tilapia system after playing with a small goldfish setup last year)

- three sisters garden

- small fruit orchard (in the works for this year)

- salad bar in bed over a rabbit run

- pet rabbit that serves as a general recycler and producer of some excellent manure

- indoor sprouts

- modified square foot gardening

Upcoming/potential projects:

- soilder fly bin

- vermiculture bin

- outdoor pond for trout in an open loop aquaponics system

- solar water/air heating in hoop house and/or garage aquaponics

- additional GB's (likely separate, wicking) in aquaponics setup

- duckweed tank

This is all in a suburban setup, with small lots; my yard is approximately 35'x100'.

Anyway, thanks again for all the feedback thusfar, and for all the great info that is posted on this site. During the initial part of my aquaponics journey, everything that I came across pointed to the use of F&D beds, where the GB served to capture solids, and act as the biofilter (makes me angry just to think about it now). Thanks to sites, such as this one, I am much better informed now and more confident about a successful outcome.

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Hi Ed,

Anyone know how to include a larger version of the images that I post? I would like to include updates as I proceed, but the images that I am adding are showing up rather miniscule.

Are you aware that, if you click on them, they expand to something larger.......and that, if you click on them a second time, they enlarge even further.

Where you see very large images, it usually means that they are an attachment link out of a photo storage program like Picasa or Photobucket.

They look good but, from a forum operator's perspective, they have a dark side. The links can be become faulty.....or they'll be broken when the images are moved about at the storage program end......or the poster becomes petulant and decides to disconnect the links. Anyway, the end result is that they are no longer available to the people who demonstrated the commitment to read/follow the thread.

Having said that, I'm probably not as glued to the idea of uploading the images into the forum......or of the technical value of a lot of forum content once it gets past a certain age.

You choose which system works best for you.

I started this thread as my first post because I am anxious to work out some final details before plumbing out and starting the system this Monday. Yet, I was remiss in introducing myself (although this likely belongs in a different section). I am a backyard sustainability enthusiast with emphasis on food production. To borrow from Gary's nomenclature, I would say that I am into Microponics and dabble in:

- hens for egg production, manure for the garden, bed prep after growing cover crop, and compost turning

- raised garden beds, which are covered by a hoop house over the winter, and am considering converting to wicking beds

- indoor aquaponics setup (just starting a tilapia system after playing with a small goldfish setup last year)

- three sisters garden

- small fruit orchard (in the works for this year)

- salad bar in bed over a rabbit run

- pet rabbit that serves as a general recycler and producer of some excellent manure

- indoor sprouts

- modified square foot gardening

Upcoming/potential projects:

- soilder fly bin

- vermiculture bin

- outdoor pond for trout in an open loop aquaponics system

- solar water/air heating in hoop house and/or garage aquaponics

- additional GB's (likely separate, wicking) in aquaponics setup

- duckweed tank

This is all in a suburban setup, with small lots; my yard is approximately 35'x100'.

Anyway, thanks again for all the feedback thusfar, and for all the great info that is posted on this site. During the initial part of my aquaponics journey, everything that I came across pointed to the use of F&D beds, where the GB served to capture solids, and act as the biofilter (makes me angry just to think about it now). Thanks to sites, such as this one, I am much better informed now and more confident about a successful outcome.

Eddie, I suggest that you cut and paste this content into a new system thread in your own name......and leave this one for the discussion soil-based garden systems......and the occasional treatise on adult learning.:wink:

Sorry 'bout the hijack.

Gary

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Gary,

I have clicked on the image twice, and although it opens in unique windows, the image remains small. On journeyman's site, the image expands when clicked open.

On another note, what are your thoughts on combining the sump/primary biofilter and placing this after the GB's and before the fish tank? The proposed flow would be FT -> radial flow/matala filter -> GB's -> sump/moving biofilter -> FT. Journeyman recommded that I instead place the biofilter after the mechanical filter and before the GB's, and I would like your take on this since doing so would require me to add a sump tank in addition to the two filter tanks.

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Hi Eddie,

On another note, what are your thoughts on combining the sump/primary biofilter and placing this after the GB's and before the fish tank? The proposed flow would be FT -> radial flow/matala filter -> GB's -> sump/moving biofilter -> FT. Journeyman recommded that I instead place the biofilter after the mechanical filter and before the GB's, and I would like your take on this since doing so would require me to add a sump tank in addition to the two filter tanks.

When all's said and done, the placement of system components in a water column often comes down to pipework and valves.

Take a close look at "The Queenslander" schematic that I've attached.

In normal circumstances, I operate the system with Valve B fully open and I use Valve A to regulate the flow through the growing systems. If I want less water to flow through the growing systems, I open Valve A up a little - if I want more (or all) of the water from the fish tanks to go to the growing systems, I just shut Valve A

If you shut Valve B and fully open Valve A, the water recirculates from the fish tanks to the filtration system and back into the fish tank.....and you can isolate the plant growing systems from the fish tank and filtration. This is useful in the event that you can treat a disease or infestation in one system without impacting the other......or if you want to shut off your growing systems to minimise overnight heat loss....while leaving the basic aquaculture unit recirculating happily.

This design is the culmination of every useful thing that I've learned......it's the Microponics approach to backyard fish production.

A couple of other things to note:

  • The moving bed bio-filter and sump are combined.
  • The location of the duckweed tank is deliberate - it's an integral part of the filtration system as much as it is an efficient producer of hight quality plant biomass.
  • The Queenslander is designed to work with any hydro or soil-based growing system......or combination thereof.

Gary

post-2-13795791101074_thumb.jpg

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Hi all

EG have posted a werry detailed description drawings etc on his web site - thank you eg for that.

Eddie I hope you will make a detailed layout of your variation of the erathan bed

cheers

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Hi Ande,

Thanks for the heads up on the the new information......and you're right, it's very detailed.....indeed, it's an excellent presentation of the beds and how they work.

In the post, Paul says......

You will want to run the system for a week before adding fish to the tank. The water will be dirty but will clear up very quickly if you have your set up right. That will give you time to check the water parameters over the week to be sure it is satisfactory to your fish. If it is not right, avoid trying to change it, the system will work it out one way or another. Just keep it running. There is no great need to “cycle” the system as the soil will contain all the nitrifying microbes you can handle and will leach into the gravel substrate where your water flows very quickly.

Soil-based growing systems do offer some advantages over the media grow bed, NFT and DWC growing systems commonly in use in aquaponics.....but, if coupled in a direct loop with the fish, they come with some risks, too.

Paul, I note your claim that you've had no problems with a direct relationship between the soil and your fish, so what advice would you provide as to how your beds should be managed to avoid issues.

Gary

Admin Note: Now that we're back on track, I've tidied up this thread so that it can function as a useful discussion on soil-based growing systems.

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Hi Eddie,

I am not planning F&D earthen bed, but rather a continuous flow bed where the water level is below the soil line. Geo textile would separate the hydroton from the soil and serve as a wick.

Paul's latest post makes it clear (for as much as it might not have been earlier) that the Earthan bed is a wicking bed with subsurface continuous flow watering - rather than the static water reservoir that is a usual feature of a wicking bed.

While wicking beds.....and subsurface continuous flow grow beds.....are increasingly common features of the backyard food production landscape, combining them is a very useful innovation.

The major downside to wicking beds is the formation of anaerobic conditions in the water reservoir. It naturally follows, therefore, that anything that keeps things smelling nice, is a desirable thing.

In this manner, there wouldn't be much leaching from the soil. The soil would be a mix, with only organic components. Does this change your perspective Gary? And Paul, is this more or less what you are doing, which seems to be working so well?

The fact that something is organic doesn't automatically mean that it's not dangerous to fish. I can think of a variety of organic substances that will kill fish in very short order.

I'm not suggesting that it's not possible to integrate soil-based gardening systems.....even directly......but it would require some careful thought.....and even more careful management.

Gary

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Glad to see the discussion focused in a positive direction, and much gratitude to Paul for so generously sharing his knowledge and experience. That post on EG was excellent. As far as potential harm to fish relating to compounds in soil, I am intrigued and would love to see some discussion on this.

Perhaps this is simplistic, but much of my approach to backyard homesteading draws on permaculture principles. As such anything that mimics nature and emulates natural relationships is right up my ally. That's primarily why the earthan beds are so appealing to me (that and the fact that I love soil). It seems to me that fish in rivers and lakes are exposed to soil, so I am curious about what could be harmful to fish in soil in a controlled environment.

I'll post follow ups as I develop my system.

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Hi Eddie,

Perhaps this is simplistic, but much of my approach to backyard homesteading draws on permaculture principles. As such anything that mimics nature and emulates natural relationships is right up my ally. That's primarily why the earthan beds are so appealing to me (that and the fact that I love soil).

Wicking beds, the precursors to Earthan beds, are natural partners for any backyard aquaculture system, in my view.

The incorporation of a continuous flow of well-aerated water into a wicking bed arrangement.....or, as Paul also said, the addition of layer of soil to a continuous flow grow bed....makes a great idea even better.

It seems to me that fish in rivers and lakes are exposed to soil, so I am curious about what could be harmful to fish in soil in a controlled environment.

I'm not suggesting that there's an automatic connection between soil and fish health problems. Fish, rivers and lakes all form part of large complex ecosystems which, by their very nature, tend to be relatively stable.

Even then, the introduction of fish, plants, duckweed and similar from the wild should be discouraged.....because of some of the unhelpful organisms (like internal and external parasites, pathogens, white snails, etc) that may accompany them. Similarly, introducing farmed organisms should also not occur - for the risk to wild fish and animal populations that it poses.

Backyard food production systems are (by comparison) microscopic simple ecosystems - far less stable and resilient.

Let's also remember that, because a fish looks OK, doesn't mean that it's fit to eat.

I suggest that the composition of the growing mix would also need to be very carefully monitored. Sudden increases in nitrogen levels (in conjunction with a high pH perhaps) could pose a real health risk to the fish in the system.

To summarise, I'm not saying that the recirculation of water from a soil-based growing system through a fish tank is automatically going to be problematic.....but it is a risk that requires acknowledgment - and management.

Gary

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Worthwhile point regarding macro/micro systems, and it seems that we agree that success with soil media in aquaponics comes down to controls. Hopefully I manage this correctly; I setup my first earthan bed, as described by Paul, and the system has been running for 24+ hours. I transplanted some tomatoes, broccoli, eggplant and peppers.

I'll post progress pictures and try to document how this develops as I go; I'm sure I'll need guidance along the way, and perhaps someone can benefit from my successes - and hopefully not too many failures.

Here's a diagram of the final layout. Thanks to all for the input/help thus far, and especially to Paul for all the help.

post-8141-13795791107987_thumb.jpg

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Hi Eddie,

Since my paramount concern is water quality for the fish, I'm probably still leaning toward a separate loop for watering the wicking beds.

A separate loop would ensure that there are no cock ups to influence the fish' well-being and you have greater flexibility in the placement of the beds relative to the fish tank.

I'm not saying that a direct connection won't work.....but, if it's not there, then there is nothing to go wrong. As Paul observed here several days ago, there's not much that can go wrong.....but it is possible. To large measure, it comes down to maintaining strict control over what goes into and onto those beds.

Gary

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Hi Eddie,

To large measure, it comes down to maintaining strict control over what goes into and onto those beds.

Gary

I agree and my greatest exposure is probably making sure that I only add fully matured compost from the yard, or stick to castings. I have not used any sprays of any kind except for compost tea and lactobaccilus bacteria, but I don't think that either would be an issue.

I have the earthan bed running and with some plants, and will set up a second bed shortly with continuous sub-surface flow using only hydroton. While I hope to have success in both, it will be interesting to see how the same plant type/seed, sowed/transplanted at the same time would fare in these side-by-side systems.

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Hi Eddie,

Outside of toxic substances in the growing mix, my major concern lies in the introduction of solids into the fish system. The purpose of mechanical and biological filtration is to minimise the presence of solids in the system so I'm still struggling a little with the idea of introducing external solid wastes.

There are a number of reasons for minimising the existence of solids in an aquaculture system with the most likely risk being an increase in biological oxygen demand - assuming the presence of volatile organic compounds in the solids.

Once again, I'm not saying it can't be done......but rather that is comes with risks - and that there are other safer ways of achieving the same result.

Comparative trials are always useful.....and interesting. There's nothing like experience to quell the unsettled mind.

Gary

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Hi Ande,

I can't quite grasp the connection between the material on pages 11 and 12 and what happens in an Earthan bed.

I can appreciate the information in the context of pond ecology but how is that relevant to an aquaponics system?

The presence of solids past a certain point are undesirable.....indeed prospectively hazardous to fish. I'd have thought that anything that failed to optimise removal of solids (much less add to the existing solids load) would be seen as problematic by Paul.

And it begs the question.....why have the fish exposed directly to soil-based beds if it is not necessary? What is the benefit of doing so that outweighs the prospective risks.

Gary

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Gary,

Thanks again for your continued feedback/advice. I'm hoping to keep from introducing solids into the system since the water flow does not come into contact with the soil at any time, and I do not plan to top-water. Also, the flow from the GB goes to the solids filter and then to the bio-filter, so if anything does get in the water column, I'm hoping that it is captured in the filtration.

ande,

Thanks for that link. Doesn't the oxidized layer section, as discussed in that white paper, refer to a layer of sediment maintained at a bottom of a pond? In the earthan bed setup, there is no intended sediment layer and any solids should be removed by the solids filter and purged regularly.

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Our experience with the Earthan Beds shows no issues with solids without filtration.

The school system featured in the article explaining Earthan Bed construction is 60m2 of grow space and all the beds are Earthan Beds. This runs on the central 4000 litre fish tank continuously. It does not have any solids filtration at all and no issues with plant growth. In fact the permiculture guys running the garden are "amazed" at the growth. This same school also has lined raised beds build by a permiculture group with drip irrigation and they can not match the growth performance of the Earthan Beds. Has been running for over 2 years now.

The other example is the Basin View project. It is somewhat larger and includes floating rafts and clay/gravel media beds which the water flows through prior to entering the Earthan beds. The flow of the system has been extensively described on our site. These act as prefiltration (by design). It does not have any specific solids filtration but it is only running 6000 litres of fish tanks which is a large variation to the school project in terms of ratio of beds to fish. Over a year old now.

All of the beds are out in the weather which makes them part of the water catchment when it rains. They do become quite turbid during torrential rain but the water is crystal clean within 24 hours. Both systems have experienced extremely high rainfall for long periods of time as a result of flooding in both regions and they still stand well without issue. Nor do they require any pH management or nutrient addition. This is done organically through the surface of the soil.

Smaller systems will be a little more dynamic by nature but will perform the same. It is very important to not overcomplicate the process. So some trust is needed they will do what they need to with very little intervention from you. Young plants or seeds will require some surface watering to get them established. Other than that they will grow just like any soil raised garden bed if you treat them as such.

While both Earthan Bed and fish tanks are directly connected without filtration there are simple valves to isolate them should the need arise. To date that need has not surfaced outside of cleaning fish tanks from time to time. Neither system has had any water quality issues (carbon, nitrogen, oxygen) or otherwise.

Paul

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