Backyard Aquaponics
A place to discuss aquaponics

Hello guys,
My first post's link is below,
http://www.backyardaquaponics.com/forum/viewtopic.php?f=45&t=29808

So we came up with some numbers on how and what size should our system be built like. We did some research and came up with those and below are the details.

Basic information,
Location of the system : Gujarat, India.
Temperature Condition : Highly diverse.
Type of System : Deep Water Culture.
Type of Crop : Lettuce/Cabbage.
Type of Fish : Telapia.

Parameters of system,
Fish Tank : 1200 litres
Clarifier / Mech. Filter : 300 litres
Biofilter : 52 litres
Growing Throughs : 800 litres
Sump : 30 litres

When running,
Number of Fish : 50 to start with.
Each Fish weight (approx) : 500 grams.
Number of seedlings : 50 to be planted.


My questions are,
1. Do these parameters and ratios look good ?
2. What advice would you give for this system ?
3. What can I add or subtract to make it better ?

I would like all of you to help us with our systems and make a greener future.

Hi Sandilya Jha,

A few questions:

(a). Are you going to have any gravel filled grow beds in the system, or is all your bio-filtration coming from the 52L?... and what sort of bio-filtration media is this?

(b). Will the fish be going into the system at 500gm each, or will they be going in as fingerlings and grown out to a size of 500gm?

(c). Are you planning on adding more DWC grow bed area/plants?

(d). Why a 30L sump?... In warm weather and with good plant growth, this could very well run dry in a day.

Thanks a lot for the quick reply !

a. This is one of the most confusing part for us. But we have a plan to bypass the outgoing line from Fish Tank throught a media bed ( this is where we plant our seeds at stage 1 ), and also have a bio filter for the post connected DWC, I'll try to draw a quick visual diagram and attach it in the post.

b. Just because we are testing the growth and wanna set the system more biased for the "crop-selling project", we will be adding the ~500gm fish directly; we can implement the fingerlings in the test phase #2.

c. No we are restricted to the area scaling of the system. So we do not wish to add more DWC.

d. Nice suggestion ! We will plan on a better sump; also any suggestion about how large should it be ? I guess a 100 litre would not dry out.

I also forgot to mention, the system will be in a closed area and not a farm, grassland. So the climate would not affect us directly i.e, the harsh sun and the rains.

The image for Question "a",


I have also attached it !

Thanks again !

Hi Sandilya Jha,

(1) don't make new threads, stay with one thread - it makes it easier on people reading your situation history.
and it helps stop the forum from being cluttered up.

Use the method here to post pictures... viewforum.php?f=4

(2) 50 fish is probably a bit too much for the system you are proposing. You may get there in the future if it is a 1200L round aquaculture tank, but there are lots of reasons this will be challenging. It is 25kg of fish as planned. Adding that many fish in one go - if not fingerlings - will probably result in the system failing.

(3) The sump and some storages are undersized and will prove to be ineffective over time. A better size for the sump would be 500 L IMO (certainly a lot more than 30L and 100L).

(4) To handle your fish load you will need a larger biofilter - probably multiple 200L drums would be better.
Ultimately will need more wet media for your stocking rate.

(5) positive news is that you can probably have a larger number of vegetables growing.
Lettuce and Asian veg will be OK, not sure how your cabbages will go (depends on variety)
I wouldn't do the seed raising as you have shown, better and less room to use commercial seed trays then go into the DWC.


I think your layout is a too complex. Try looking at the FAO Small scale aquaponic food production publication. http://www.fao.org/3/a-i4021e.pdf (or Google it)

A good thread here is Andreas "Crappy Basil Growers are us".
viewtopic.php?f=18&t=16235 (go to pages 90+).

>> No we are restricted to the area scaling of the system. So we do not wish to add more DWC.

there are ways to be smart about this to optimise growth area.
perhaps advise on the dimensions of the area you have available and dimensions of fish tank, beds etc.

Sorry for the super late reply, we have been constantly reading about the topic to make ourselves stronger. We have made a lot of changes to our system design and concept ! .. Also,

1. I wont be making new posts sorry
2. We are going to opt for fishless cycling.
3. We have now planned for a 500 litre sump ^_^
4. We also planned for a better bio filter .. details incoming soon.
5. The link you provided is now a bible for us. Thanks a lot for the support !

I'll now make a new post about the new design and few questions before planning the final layout !

Cheers !

Guys, I have the following questions.

1. We are going to use a moving bed biofilter. Is this ok ?
2. According to the calculation on the internet, the Biological Surface Area ( BSA ) that we should be using ranges from 250 to 300 m2.. The calculations are based on a. max fish load of 15kgs b. fish tank of 1000 litres. That means we need a k1 or k2 or k3 media of around 700-800 litres.. !! Can this be reduced ? Because the media is very costly for us.
3. We are very much confused between two types of canals, a. the first where water touches the Styrofoam sheet and needs air pumps .. b. Kratky method, where the water does not touch the sheet and does not require air pump. Which one should we use ? We are planning for a system with 85-100 crop heads.

1. Yes provided you also have good solids filtration prior to the DWC. Fine solids can stick to the roots of the plants in the DWC and smother them so you probably should remove these. You can try it without and see how it goes but try to leave space for something like a Static Upflow Filter (SUF) in case it needs some filtration and maybe something to mineralize the filtered solids as well (so that the nutrients can be used in the system if needed).

2. Based on the stated capacity (here's one sellers claims - https://www.ebay.com/itm/Moving-Bed-Filter-Media-2-Cubic-Feet-56-63-Liters-K1-K3-FREE-SHIPPING-/162160799178) of the bio-media and the max fish load I think your calculations are off but I'm not sure where you're getting your calculations or what your setup is. I'd probably double the amount needed just to be safe (looks like somewhere in the 3 to 4 cubic foot or roughly 50 to 100L of media. Are you figuring in any biofiltration provided by the underside of your DWC rafts, the sides of the canals and the roots of the plants (for any parts of these that are wet)?

3. - I'd go with the aerated version (method a) to start out, not the Kratky method. If I remember right the Kratky method you would fill up the DWC trough once and then allow the water level to drop as the plants grow (since their roots get longer). If you aren't trying to grow just one type of plant there can be issues with some plants not getting their roots down in the water because they don't grow as fast as others. The other thing (if I understand this method correctly) is you would only pump water into the trough at the begining of the cycle. I suppose you could suspend the rafts over a DWC with flowing water and that might work as well but you then need to get the roots long enough to reach the water in the first place. You may be able to get it working either way but I'm not sure and I think the aerated method may be your best bet.

Thanks for the reply !

1. Yes we are going for a RFF prior to biofilter and also a extra mineralize tank for the solids that we collect from RFF. I did try to understand how static upflow works and will keep a additional space for it. Will this work ?

2. I got the calculation from this website,
http://blog.zipgrow.com/biological-surface-area-in-aquaponics/

and it quotes the following,
"Calculating your BSA
Remember: as an absolute minimum, your system needs at least:

2.5 ft2 of BSA/gallon of water (at low stocking densities and low feeding rates)

For a healthier system, we would recommend:

10 ft2/gallon of water OR 100 ft2/pound of fish

EXAMPLE:

If you're stocking fish at 1 pound per 10 gallons, for every pound of fish, you'll need 25 ft2 of BSA - This will be the amount you'll need for adequate waste and ammonia processing."

The system we planned has a gross fishtank water volume of 880 litres and max fish weight of 15 kg.
So according to above,
Respective of 880 litre, we need 215m2 of BSA
Respective of 15 kg of fish, we need 306m2 of BSA.
Is this correct ?
The website you gave provides a simpler calculation too.
Actually, the k1 we found has a SSA of 350-400m2/m3. Which means it has BSA of 350-400 per 1000 litre.
and hence i concluded we need around 800 litres of bio media
Something does seem wrong. Can you guys please help me with this ?

3. We are on with the aerated version !

Thanks !

First things first - Keep in mind that it takes awhile for the bacteria to get established in your system and the filtration capacity won't start out ready to go. You have to cycle the system without killing the fish because of high ammonia or nitrites. Usually this takes at least a couple of weeks to a month. That's a pretty high fish load for getting started so you're going to have to be extra careful.

It's likely that Tilapia will also begin reproducing in the system so that will up the filtration requirements and I'm not certain how. Watch the ammonia and adjust your filtration if needed.

See my other comments and instructions below.

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It looks like you have planned a good sized DWC bed which will help with the biofiltration so you shouldn't need as much media as what your calculations show. The media in the seedling bed will also help.

Rather than recalculate based on what you have lets look at it a different way (To follow along use the FAO manual Appendix 4 on page 191 and 192) - for this you'll need to know how much protein is in the fish food you're going to use. Since you're growing Tilapia we'll say 32% if you go higher or lower you'll have to adjust these calculations. You have to plan for the most filtration you'll need so you'll also have to use the final size of your fish in the calculations - I'm just using what you've given me which is the beginning size.

-------------

You have 15Kg of fish eating 1% of body weight or 150 gms of food. Nitrogen makes up about 16% of the protein in this food and the food is 32% protein. To figure the amount of ammonia that needs to be converted -

150g X 32g protein/100g Feed X 16g N/100g Protein X 61g wasted N/100g N X 1.2g NH3/1g N
= 5.62 g NH3

Using the FAO 0.57 number for conversion you would need 9.86 m2 of media surface area to process 5.62 g of NH3 per day. Basically 5.62g Ammonia X 1m2/0.57g Ammonia = 9.86m2

So for K1 which has a surface area of 500m2/m3

9.86 m2 X 1m3/500m2 = 0.0197m3 or 19.7L of K1 needed

-------------------
Lets instead look at their high and low numbers for ammonia conversion. According to the FAO the amount that can be processed per square meter varies from 0.2 to 2.0g per m2.

5.62g Ammonia X 1m2/0.2g Ammonia = 28.1m2 and you would need

28.1m2 X 1m3/500m2 = 0.0562m3 or 56.2L of K1

------

5.62g Ammonia X 1m2/2.0g Ammonia = 2.81m2

2.81m2 x 1m3/500m2 = 0.0056m3 or 5.6L of K1

This looks a lot closer to the amount needed that was listed on the link from the seller on ebay. I was talking around 50L based on that and then doubling it to around 100 just to be safe so it looks like this at least jibes with the other. Here is a quote from another source - http://evolutionaqua.com/acatalog/K1_Media.html - "50 Litres of K1 media will handle up to 250 grammes of food per day".

I think your DWC and media bed also add an extra safety margin but you have to go through these calculations again using your fish feed because it has to be based on the protein content of your feed, how much you are feeding and the final grow out size. Usually with adult fish you'd be feeding around 1% of body weight and 2% or more for younger fish. Feed for younger fish is also higher in protein.

Hopefully if anyone sees any glaring errors they'll chime in

Super reply Scotty ! Thanks a lot.
Yesterday we visited the regional fishery office and we ran across something bad. The Indian Fish ACT rules are not yet clear on where I live. We probably have to ditch Telapia because apparently its banned. But still, its not clear. We probably to use the Catla Carp which is quite common where I live.
I'll let you know the food and % protein we are going to use for this. Thanks again for the super calculation ! Am not worried about purchasing a ton of media now.
I also mentioned earlier that we have opted for fishless cycling and have no plans to add the fish directly.
We also dont have any media beds for additional filtration. Basically its just a DWC system.
I have made a noobish 3d design of our system in TinkerCAD ! Is anyone of you intrested in looking at it ? Or should I just post the simple 2D diagram of our system on which you people can guide us with more advices ?

Cheers !

Greetings !
Its difficult to find all the correct things we need.
Which one of the following seems good for our system ?

a.
https://www.easypets.in/accessories-spares/ocean-free-limewood-air-stone-marine-tank/p-5344535-29781209199-cat.html#variant_id=5344535-29781209199
b.
https://www.easypets.in/aquarium-round-air-stones-hl-01#variant_id=5344535-92271864952
c.
https://www.easypets.in/boyu-mineral-sand-air-stone-01#variant_id=5344535-89101495294

The first one looks good but it creates super fine bubbles that almost cloud the water with white mist of air. Its actually for protein skimmer for a marine tank. Can we use it ? The others are simple disk and cylinder mineral stones. ^_^

We tend to pump around around 4 litre per minute with each one of them per m2 of DWC area.

bump.

Any help will be appreciated.

Not a clue on this question, you might need to do some testing on this one to see what works best.

No problem we'll try the testing of stones.

My next question is, is there any guide or guidelines I should follow for the aeration system.
We have the DO kit handy to keep the levels above minimum always. But how much aprrox litre per minute of air should we pump at all stages, like the DWC, FT and biofilter ( moving bed ) types.

We have the following setup,

a. 1xFish tank from an IBC .. Total Volume = 800 litres.
b. 4xDWC cut using IBC, each DWC is 1m2 .. Total volume per DWC is 300 litre.
c. Biofilter is approx of 150 litre.. How much approx pumping of air to move it in boiling motion.

The pump we designed turns the system volume once per hour. Capacity of pump is 3000/hr at minimum and our system is of 3000 litre.

The hypothetical system has the following aeration,

a. The fish tank will have 2x airstone generating 4 litre per minute air each.
b. Each DWC has 10 litre per minute.
c. The biofilter has 20 litre per minute.

Can we go ahead with this ? Will this satisfy and maintain the minimum required DO ?

Thanks !

There is enough I don't know about your system that I can't answer those questions. I might not be able to answer some of them even if I did know everything I needed to but I'll try to get you started where you can find what you need.

For the aeration in the biofilter to get the media boiling (it should look like a light boil unless you're trying to clean the media) - This is going to vary with the amount of media, type of media and shape of your container - Here are some pump recommendations based on media volume (the numbers in the pump name are the max LPM the pump delivers (at least in this case)) - http://www.evolutionaqua.com/acatalog/K1_Filter_Media.html. I think their estimates of the pump needed might be too high but can't be certain.

Take a look at this and see if it answers your questions on aeration in the DWC troughs - http://teca.fao.org/read/8397

Tilapia are very durable fish and can tolerate very low dissolved oxygen levels. On the other hand, they'll grow better with good conditions so if you're planning on lots of fish then you need to aerate (keep the DIO above 5 and preferably higher). If your stocking rates are low just water movement may be enough. Given what you've told me I would aerate the fish tank especially if you see the fish hanging out up at the top of the tank like they need air. If you want to figure this more accurately then this article by Dr Rakocy should help - https://thefishsite.com/articles/tank-culture-of-tilapia.

Hope this helps