Things I have learnt since starting hybrid systems.

[Kobus Jooste]

The most important thing is to abandon the single pump lay-out if you want to have media beds and rafts / NFT in a compact space.  In the past, I could drain gravel beds into rafts and then to a sump full of netting.  This kept the water in the system clear and the roots in the rafts looking good.  My new lay-out is NFT above and raft at the same height as the media beds, thus the single supply line I have been using is really too dirty for NFT.  Option 1 is in line filters, and option 2 is small secondary pumps for the NFT.  I'm going for the latter.  A high head low wattage pump will be tossed into the sump as soon as I have installed a internal configuration that settles the solids out prior to it getting to the pump.

 

The second issue I am picking up is that hybrid systems tend to have "just enough" gravel rather than surplus, which means that fines and even intermediate solids seem to stay in the system's water.  I picked this up with the sump retro-fit.  I therefore think that if you are going to run a stacked design with raised beds and lots of media-less culture, you need to find ways to settle out fines the way it is done in raft-type systems, but without discarding it.  We are therefore talking in the direction of mineralization / digestion sections in our AP systems, but not yet solids removal.

[Sahib Punjabi]

Hey Kobus :-)

 

While in principal I follow your logic, I have managed to have a sort of mixed or as you call it, a "hybrid" system with one pump. I think that my "hybrid" system is reasonably successful, but do admit, it has not even been half a year, so time will be the judge of that. 

 

At present in my "hybrid" system, I have one Beckett 1150 gph pump located in my 1,000 gallon tank that houses about 200 small Koi. I have placed the pump in a "Milk Cart" that is surrounded by filters, so water has to flow through them before it is taken up by the pump. I have then diverted half of the flow back to the fish tank which at present provides extra aeration ( this is further split so that it can feed a 4x8 hydroponic media grow bed with water returning back to the tank). The other half of the water is pumped up to two 50 gallon tanks with additional filters, solid removals and mineralization before the water is fed to the DWC bed. Just prior to water entering the two 50 gallon  tanks (one set up as a swivel), I have taken an output for my three 48ft NFT channels (3 inch round pipe which I separate at the 1st 20 ft section by going down to 1/2 inch...this reduces the flow and keeps the water balance in check). So far, I have not noticed any heavy sludge / solids build up in either the DWC bed or the NFT's.

 

I have plumbed a faucet outlet in the two 50 gallon "filter tanks" and use end tank outlet to feed the recirculating media filled wicking beds that are tied into the system. Yesterday I cleaned the 'Milk Cart" in the Koi pond. The filters were rather loaded with sludge and solids. I washed these into the wicking beds so the there was no waste. All the water returns back by gravity so only one pump is being used. 

 

I do concede that point that there is a limit to "Gravity" fed beds. Should I want to go higher re verticals, or lower than the return, I will need an additional pump, either to act as a feeder or as a sump. Yes, I do believe that one should install some means of filter re solid/sludge removal around the pump as well as have "socks" on the return pipes. This will certainly help in DWC & NFT's :-)

 

God bless

[Kobus Jooste]

Thanks for some more detail on your very nice system - towards the end of your message, you got to the core of my design's "1 pump does not work" dilemma: I am working on too many levels, and because I have a lot of media beds and a tank buried deep into the soil, I did not want to go for a net around the pump as it will take some acrobatics to recover the pump should it ever need work.  I thus get a "dirty" stream of water into the gravel, which is not ideal for NFT or rafts.  I would be able to push the height to get from the tank level (basement), over the bed level (1st story) and then up to the NFT level (2nd story), but the water is still untreated.  Thus in comes a clarifier at ground level and a second small pump for NFT.  In all, from the bottom of my fish tank to the top of my NFT, I cover around 3 meters in vertical climb.  The greenhouse is therefore a 3 m x 3m x 3m "cube" with structures along the sides and the core open for me to walk around in.

Sahib Punjabi said:

Hey Kobus :-)

 

While in principal I follow your logic, I have managed to have a sort of mixed or as you call it, a "hybrid" system with one pump. I think that my "hybrid" system is reasonably successful, but do admit, it has not even been half a year, so time will be the judge of that. 

 

At present in my "hybrid" system, I have one Beckett 1150 gph pump located in my 1,000 gallon tank that houses about 200 small Koi. I have placed the pump in a "Milk Cart" that is surrounded by filters, so water has to flow through them before it is taken up by the pump. I have then diverted half of the flow back to the fish tank which at present provides extra aeration ( this is further split so that it can feed a 4x8 hydroponic media grow bed with water returning back to the tank). The other half of the water is pumped up to two 50 gallon tanks with additional filters, solid removals and mineralization before the water is fed to the DWC bed. Just prior to water entering the two 50 gallon  tanks (one set up as a swivel), I have taken an output for my three 48ft NFT channels (3 inch round pipe which I separate at the 1st 20 ft section by going down to 1/2 inch...this reduces the flow and keeps the water balance in check). So far, I have not noticed any heavy sludge / solids build up in either the DWC bed or the NFT's.

 

I have plumbed a faucet outlet in the two 50 gallon "filter tanks" and use end tank outlet to feed the recirculating media filled wicking beds that are tied into the system. Yesterday I cleaned the 'Milk Cart" in the Koi pond. The filters were rather loaded with sludge and solids. I washed these into the wicking beds so the there was no waste. All the water returns back by gravity so only one pump is being used. 

 

I do concede that point that there is a limit to "Gravity" fed beds. Should I want to go higher re verticals, or lower than the return, I will need an additional pump, either to act as a feeder or as a sump. Yes, I do believe that one should install some means of filter re solid/sludge removal around the pump as well as have "socks" on the return pipes. This will certainly help in DWC & NFT's :-)

 

God bless

[Harold Sukhbir]

Hi Kobus,

That's the same dilemma I was faced with. Having to retrofit and existing system. I think this will be a matter of course. Since the initial designs, thoughts start to expand and then the inevitable......make more efficient or exotic. Going up top with NFT's as the first line requires high filtration and rather than a complete redo to facilitate the one pump it just makes plain sense to slow down, settle, and then push with a new pump. Lately I've been making some moves to go to the commercial level and this has been reflected by my recent system upgrade, where I'm pushing everything to the max. I guess my goals are changing. I'm liking the idea of using the milk carton Sahib.

[Kobus Jooste]

It seems as if "going commercial" for many people appear to include a need to have greater stocking densities of fish.  I assume this is in order to get the maximum benefits out of the capital put into an area, to reduce the footprint of the system by having more nutrients in a smaller space or for whatever design purposes people come up with.  It will be interesting to keep an eye on commercial system developments to see if it finally morphs into something totally different from home aquaponics, or if it will remain pretty much the same thing done on a large scale.

[Eric Warwick]

What if the fish tank over flows to the gravel bed which overflows to a sump tank/ deep water culture, then a pump bring the water up through nft and goes by gravity, with variability in the density in the nft.

[Kobus Jooste]

You pretty much describe the first hybrid system I built apart from the fact that the FT overflowed into media beds, which then drained to DWC and then into a sump.  For the system I have now, I wanted to focus on a smaller footprint (a basic 3 m x 3 m cube) and aeration cascades which does not allow the same kind of configuration I had before.  Our commercial design again has the sump, fish tanks and rafts all at the same height, and only the gravel beds elevated.  Typically AP systems would take on a elongated shape as they expand, allowing the configuration you describe above.  Cubes don't allow for that - the highest point are towers, not gravel.  You cannot overflow into these, and neither can you send "dirty" water up to them.  For Cube shapes, I think a "Clean line, dirty line" configuration with two pumps is likely the ideal for me.

Eric Warwick said:

What if the fish tank over flows to the gravel bed which overflows to a sump tank/ deep water culture, then a pump bring the water up through nft and goes by gravity, with variability in the density in the nft.

[AJ Grottke]

Kobus, did your first hybrid system work out for you; did the gravel bed filter out enough stuff for your DWC and NFT?  I have a system similar to your 1st system,  which i just started cycling yesterday.  But i am running a "clean line" on a separate pump for my NFT which is in the sump after my gravel bed.

[Kobus Jooste]

AJ: The fines always seem to make it through the gravel, which is why I now want to have a sump full of media to filter out the fines before I send the water on tho the DWC tanks and towers I have.  The plants are alright with the current configuration, but I can potentially do better with the clean line configuration.  In my first system the raft bed production was also fine for me, but as it was my first system and with little to compare it to, I could not say if the system would have been better on a cleaner line for the DWC.  Right now I have a tomato plant in the "dirty line" DWC bed that grew faster and have faster maturing fruit than the ones in the gravel.  The roots of the plants are not white, but I never get root rot in the system.  Would like to test the clean line against a year of the current design though.

 

Eric, not sure where you need more detail.  In the current configuration, the raised gravel beds were the central idea to test.  Therefore, the FT and fines settling sump (technically not a sump as the tank bottom is lower than the sump) is the lowest point, with the gravel beds and one DWC bed as the next level, followed by overhead space I'm busy trying to maximise the use of towers in.  The one bed on DWC was not planned initially - I saw issues with the permanently on pump taking too much water out of the FT in the original configuration that did not have the sump, thus I decided to run only three media beds. My current NFT and DWC are on the same line as the gravel beds, and thus do not run "clean".  I'd like to be able to run a second pump out of the sump to the towers and the media-less culture bits in order to see if it runs better.  That would give me a dirty line out of the FT to part of the greenhouse, and a clean line out of the sump to the media-less beds, NFT and towers.

[AJ Grottke]

Kobus, So for your envisioned future setup would you have 1 or 2 "sumps"?  Also what type of media for the sump filter were you thinking about using?

[Eric Warwick]

Kobus I wanted to know why, not just this is what to do, because I want try and fix it in my own way. (I guess I'm a bit stubborn)

[Kobus Jooste]

AJ: Technically I think a one sump system would be fine, with the pump at the base of the fish tank supplying the dirty line that can be seen in the pictures now.  From the sump, I want to run a "clean" line that will be used to operate the towers and NFT that is in the pictures now, plus add about 6 more vertical towers over the fish tank.  I do still have some space underneath the beds for a second sump, and have a old swimming pool sand filter body that I am busy modifying to go in there.  It would only be a volume of water to increase the total amount of water in the system though.  At present I only have 3 of the beds on flood and drain, and want to make all 4 of them media beds.  The second sump will replace the water volume lost if I take the DWC bed away and make it flood-and-drain. In terms of media - I made simple "onion bag" balls (described them somewhere - perhaps even in this group) designed to trap fines more than to be a huge surface area.  The balls float in the sump, and if they get too clogged, it is easy to isolate the sump, wash them out and set the system going again.

 

Eric: In terms of why, I can only say that this is a design that I wanted to try - not my belief that it is the only or the best way.  What you described earlier will work perfectly, but as I stated before, I set out the current unit to investigate the issue of small footprint and multiple culture levels in AP.  I don't think that there is any part of your design that needs fixing.  If anything, mine is over-complicated.  It was set up for trials and not to be the ideal home unit, although I do see some useful aspects of it.

[Eric Warwick]

Ok, that's basically what I needed to hear; whether my design would actually work, or how to fix it. Looks like the system you shared is highly efficient. The reason I wanted this type of system was the fact that rainbow trout are very picky about water quality, but I'll see how it works. Thank you Kobus. http://www.bkserv.net/images/Grin.gif