Backyard Aquaponics
A place to discuss aquaponics

Greetings,

After 6 months of fruitless farming, I've decided to build a new system. An upgrade if you will to my previous micro system. Have a look here:

viewtopic.php?f=45&t=22974&p=502425#p502425

The reason for my failure is collected fish waste in the grow bed. As can be seen in my previous system, there is no filtration whatsoever in the design. So here I am, asking all you seasoned aquaponicist (this is what we call ourselves right? ) for some advice.

Main attraction of aquaponic for me is it's low maintenance. So in that respect I would like to know what is the best design for a low maintenance system (meaning I don't have to clean it every month or so)? I don't have all day to tend to the system and would like a design that allows for almost maintenance-free system. My thought on the flow is like this:

FT -> Solids filter -> Bio filter -> Sump -> GB -> back to FT

Am I on the right track or am I missing something? Should the sump be after or before the filters? I'm planning on using a 100 gallon FT with NFT and flood and drain GB.

Thank you in advance for all your help. Keep the food revolution going guys!

There are several different ways to do the flow, it depends on what the high and low points of the system are but it looks like the order that you're proposing will work. Any thoughts on how large a system and how many fish you hope to stock? Stocking lower than the max for your filtration will help make this low maintenance. You will have to clean out the solids filter and the biofilter pretty regularly.

Looking at your previous thread I see that you did have filtration but not very much. If you are relying on GBs alone to process the waste from your fish I recommend twice as much volume of media as the volume of your FT. In the pictures it looks like you may have had less than a 1/4 of this.

People regularly say that their system failed because their GBs have clogged and people often say that relying on GBs alone is a recipe for failure. Such an experience as yours is common but more the result of not sizing the GBs appropriately to the load of waste they have been to be asked to process.

I'm building a system around a 100 gallon FT. Haven't worked out the rest yet but I believe the rule of thumb is 1kg of fish for every gallon of water right? I don't mind cleaning the filters every other weekend.


Yeah the grow bed was my only filtration. I'm aware of the errors made, and I take full responsibility of the failure. It was a test system, and I didn't give my full attention to it, it was designed to fail in due time. I even raised those issues on my thread.

So after months of collecting information and data regarding aquaponics, I've decided to build a new system.

If you want low maintenance:

ST > GB > FT > SLO >ST

Bio-filters and mechanical filters, radial flow filters etc, are not required in backyard scale aquaponics systems. A gravel filled GB fulfils both these roles brilliantly.

Mechanical filters remove valuable nutrients, especially trace elements, from the system.

But I'm planning on harvesting the solids and I don't want to clean the grow bed every month hence the filters. Leaving the filters out means low stocking density right?

You could still stock high but you'd need more grow beds - it's all relative. If you have lots of grow bed space in relation to the fish load it gives the waste more of a chance to break down and makes the load on each grow bed lower. Adding worms to the grow beds helps this process as well. You'd have the fish packed in the same space but the filtration is multiplied. You can go for at least a couple of years without cleaning out the beds this way.

Many people have run their beds for years and years without cleaning them once. One or two have never cleaned their GBs at all not even when they put the gravel in in the first place.

You don't need to clean GBs if they are sized appropriately to the load you are feeding them.

Lets say I want to include NFT into the design, what is the best flow that allows for minimal maintenance? Please help me fill in the blanks.

Start: 100 gallon FT - 40 fish maybe?
-> SLO from FT to swirl filter then drops to NFT(number of plants depends of fish stock?)
-> Continue to either flood&drain GB or constant flow GB (100 gallon)
-> Drain to sump tank
End : Pumped back to sumped tank(will incorporate venturi here to avoid air pump)

Does any of this make sense? Too many design too little brain capacity..

Does it apply to smaller systems? Most of the ones that do run for years are mostly over 1000L systems.

So basically I should do some math?

LOL. Yep.

But its not hard. 100unit FT 200unit GB

Having mechanical solids filters in the system doesn't increase the safe stocking capacity much at all. While there would be some Ammonia contained in the solids, most Ammonia is given off by fish through respiration and urination, and mechanical filters don't remove it.

For a well designed, sensibly stocked, low maintenance, backyard scale AP system the only logical reason adding mechanical filtration would be of you want to run an NFT or DWC component to the system, if so then my preferred flow layout would be:

ST > GB > RFF > NFT > FT > SLO > FT

This way the solids still make the GB's, where they can be broken down by composting worms, microbes etc, and all the valuable nutrients released.

As Stuart suggested, many very experienced AP'ers have run basic systems, with no mechanical filtration, for many years before the GB's needed cleaning out. Joel (Earthbound) from BYAP ran one for over 6 years, Murray Hallam also ran one for over 6 years. Faye from BYAP ran hers for 7.5 years.

P.S. In addition to the above comments and referencing the fact you have a smaller system... My kids have a single barrel system made from a 205L blue plastic drum, it has a 50L GB and about a 70L FT volume, it's been running for 4.5 years and there is still no obvious signs of build up in the base of the GB. I say this with confidence without digging into the GB because in addition to the bell siphon I also installed a separate overflow standpipe/removable drain, when I remove the cover from this I can see down to the floor of the GB, and there's no sludge etc around the base of the drain fitting... and it hasn't been removed in years.

That part I pretty much figured out. How do I calculate NFT and DWC GB? Want to include either one if not both of them in the system.

100 gallon FT
??? gallon sump tank
100 gallon media GB
??? NFT (no idea how many plant)
??? DWC (no idea how many plant)

Yes I do plan on running an NFT and/or DWC along with the media GB. Shouldn't it be :

ST > GB > RFF > NFT > FT > SLO > ST (surely a typo?)

Please refer to my reply above regarding the NFT an DWC calculation.

Really appreciate the insights guys.

Personally I would measure the amount of media you used in your DWC / NFT for each plant to sit in. So if you used 30 16oz solo cups you'd have about 4 gal of media for the whole system.