SOLID WASTE

[Hana Hilmi]

How do we remove the solid waste from the NFT?

[Kobus Jooste]

Typically in NFT, the solids should not get there to begin with.  In stead, you should pass the water destined for your NFT through filtration before it is pumped there.  There are a huge amount of design options, many of which are discussed in the forum (you can search the forum, group and blog sections with key words).

 

If you look at UVI style systems, you have multi-stage filtration with swirl seperation, net filters and screens before the water is pumped to rafts.  All of those are options as stand alone in smaller units, as well as putting the water through a gravel bed and then perhaps a swirl filter before sending it to the NFT.  Putting in-line filters in the supply lines clog up too fast.  I am in the process of adding a dedicated NFT line to my hybrid unit, and will do so (I have 4 gravel beds as the main filter) by operating a overflow system with a swirl seperator feeding a pump in a second box filter (basically a protective box with a fine mesh screen around it. 

 

Once the water leaves the pump, I am also considering a small in-line filter just as a precaution, but it will only be added if I think I need it.  The most important thing with a NFT system is still to have enough biological filtration and mineralisation sites in the AP unit to deal with the solid wastes though.  Just having a fish tank and NFT will not work optimally at all. You will also need to take care of degassing / oxygenation needs if you do not operate any gravel beds on flood and drain.

[TCLynx]

I run what I call a "clean water sump" and all my fish tank water flows through gravel beds before getting to the sump tank then I can pump from that sump tank up to my NFT pipes without any solids problems in the NFT pipes.  NFT is just an add on to my media based system.

 

Simply pumping from a fish tank to NFT pipes does not a functioning Aquaponics system make.  You need filtration, bio-filtration and solids filtration.

[Josh M]

I am trying to tackle this problem as well. I was originally going to have my system pump water from tank straight up to the NFT tubes then from those tubes dump into the grow beds below. There they would filter out solids and then dump back into the tank. This is opposite of what I really need. I don't want to take everything out and move the NFT part of the system down and put the grow beds on top. Just too much work. I am going to wind up having to use 2 pumps. One for the grow beds and one for the NFT part of the system. The NFT will be getting fed from a sump tank I will add that will fill automatically from overflow from the fish tank. Hopefully this will work plan to work on it this weekend cause I really want to start using my grow beds.

[Kobus Jooste]

What you refer to there is how I will be expanding onto my system too.  For a long time I tried to get along with just one pump, but unless you design very carefully for this and elevate your gravel beds quite high, it is difficult to have towers or NFT in the system that is fed on "clean" water (My system is evolving from wanting to test the abilities of growing in a very limited space to discarding that idea and spreading out, but the tank and grow beds are in place now).  I am going to have a second pump on timer in my unit, and downgrade the pump I put in originally, as it is not in need of being as strong with the NFT on a second pump.  I would suggest, if I may (if you are not doing it already), that you put the pump for the NFT line in a basket filter - some solids will still make it into your line on an unfiltered overflow. 

Josh M said:

I am trying to tackle this problem as well. I was originally going to have my system pump water from tank straight up to the NFT tubes then from those tubes dump into the grow beds below. There they would filter out solids and then dump back into the tank. This is opposite of what I really need. I don't want to take everything out and move the NFT part of the system down and put the grow beds on top. Just too much work. I am going to wind up having to use 2 pumps. One for the grow beds and one for the NFT part of the system. The NFT will be getting fed from a sump tank I will add that will fill automatically from overflow from the fish tank. Hopefully this will work plan to work on it this weekend cause I really want to start using my grow beds.

[TCLynx]

Depending on the system set up, I like the idea of having the fish tank drain into gravel beds that then drain into a "clean water sump" from where you can pump water to any sort of grow method.

I have even done a "sump grow bed" before where the water running into the bed gets filtered as it moves to the pump which is in a basket protected from the gravel.  Having the in ground sump filled with gravel also protects it from "floating" if there were a heavy rain but kinda a moot point if you are working indoors.

[Hana Hilmi]

But, with the solid waste inside the NFT, my plants still in excellent condition, green leafy and the growth is excellent. Still, I am trying putting the Zeolite (Volcanic stones) as the biofilter..will see if this could rid the solid waste. In aquarium, Zeolite makes the water much clearer for a long time without having to change the water.

[Kobus Jooste]

I have had an experimental "dirty NFT" line in my system for a while, but over time, it has started getting mucky, especially with long-terms plants in it.  I would suggest you have solids removal before the water enters the NFT.  You run the risk of smothering roots or creating anearobic pockets when you allow a lot of solids to build up in a low flow environment.

[AJ Grottke]

Kobus, u said "that you put the pump for the NFT line in a basket filter".   Do you have pictures or details on what these look like (basket filter) and how to build one? 

[Kobus Jooste]

I have not built mine yet - got the idea from a combination of a recommendation from David Waite and what Sahib suggested when we discussed adding clean lines to our NFT sections.  What I want to do, is make a basic frame out of a plastic basket or bucket.  I want to use it as a frame, to which I will attach a course screen of stainless steel mesh of the same type that gets used in the construction of water filters.  The pump will fit inside the bucket and retain its fine filter.  The space between the pump and the outer stainless steel screen I want to fill in with my cheap netting balls.  The water that I will feed the NFT with will come from a 50 mm pipe inserted into the bottom valve of my IBR tank.  I will let this rise into a 20 liter bucket mounted next to the IBR tank, with the box filter then installed inside the larger bucket.  If I find that the arrangement gets dirty too quickly, I'll put some screen between the 20 liter bucket and the feeder pipe.

[Benjamin Frimmer]

Hi Hana.  I think that the easiest and cheapest way to remove the solid waste from your NFT system is to create a "hybrid" system" rather than try to mess with baffles, artificial biofilters, and the like.

Here's what we do in our system:

 

Water from fish tank flows to a small, media filled growbed filled with gravel rocks and composting red worms.  This will not only filter your solids (the worms will eat any excess buildup for you), but it will act as a wonderful biofilter and water clarifier as well.

 

From there, the water flows into a separate, small "sump" tank, where the cleaned water is pumped via a second pump to the NFT channels.  It flows through these channels and returns to the fish tank.

 

We have been using this setup for the last 8 months and it has worked flawlessly. 

 

Hope this helps!

[the mad german]

If you have a small system or use a small bilge pump like on my system, my pump is in a12'"long 4" pvc pipe stood on end with about 30 1" holes drilled in it with the lowest holes being 2-3" from the bottom. then the pipe is placed into a cricket basket from the fishing section of walmart, the 4" pvc pipe drops into the opening perfect and even has a rubber seal so no need to solder, glue or epoxy, this allows for an even draw all the way around and if something does get through the screen mesh it drops into the space between the screen and pipe If you have enough holes in the pipe and your suction isn'ttoo strong you'll never have to worry about debris in the pump.

Sorry Kobus, didn't mean to butt in, but what he wants sounded similar to how mine is set up
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AJ Grottke said:

Kobus, u said "that you put the pump for the NFT line in a basket filter".   Do you have pictures or details on what these look like (basket filter) and how to build one? 

[Joshua Gray]

On small systems, I have seen people use a bucket with a bunch of crumpled up screen door mesh to large systems with four-stage filtration. There are excellent ideas already posted and I would like to add after you filter your water make sure it is well oxygenated for the plant roots.