Backyard Aquaponics
A place to discuss aquaponics

Thanks for those suggestions. Great ideas!



I was thinking of using 2" net pots to grow lettuce.



Not sure I understand what you mean here.



Yes...The original is about 254mm. I think of making these ones around 305mm-355mm

Is there a reason that I should have the pipe from the FT turn and go down, entering the RFF near the bottom, instead of going straight across into the RFF around midway of the RFF?
Also, the pipe coming from the FT going up inside the RFF, does that need to be near the top of the baffle?

Finally got around to expanding my AP system.
I have just completed adding a RFF and IBC DWC setup.



The Flow rate of the RFF is about 2 Litres/min, and is made from a 200litre barrel and 8litre bucket inside.
So has a retention time of about 1hr and 40mins. So plenty of time for solids to settle out...I hope.
The DWC trough is about 300 litres with the same flow rate of 2L/m, so that gives it a retention time of about 2 1/2hrs, and I have read that DWC rentention time should be between 1 and 4hrs, so I'm good...I hope.
Hope to plant some letttuce and maybe herbs this week and see how it all goes.

Raft planted with assorted types of lettuce.
Red Leaf, Romaine, Green Mignonette and 'Local' Lettuce.

It's been 3 1/2 weeks and things are going pretty good with the DWC addition.

Definitely need to try and do some Fines Filter as quite a bit of solids are still ending up in the DWC trough, but so far, doesn't seem to be affecting the lettuce. I've been checking the roots and rinsing off when necessary.
I have also been given a bunch of various size pots used in hydroponics and some perlite and hyrdoton.
Was thinking of experimenting with growing carrots or beets, or onions in the larger pots with perlite.
Do root crops do ok in DWC?

When you say "fines" just what size of a fine are you talking about?

Stainless Steel Micron Rating Examples: When filtering waste vegetable oil or waste motor oil, we all typically use filters that are rated in micron ratings. But, what do those ratings really mean? And how big is the hole? If you haven’t seen or touched an actual micron screen, it’s difficult to get a relative size in mind of just what a particular mesh might look like.


Particle (Contaminant) Size Chart in Microns


It proved to be quite a task to find a chart with accurate sizing of microns for the most common contaminants as well as common particles that are around us all the time (for comparison). This micron sizing chart is fairly complete. To the best of my knowledge, and by comparison to other particle size charts online, the list below is identical to numerous charts and data I found on the Internet – information is provided without warranty, or guarantee of accuracy of any kind. Hope this helps a little when it comes to understanding the size of these particles.

1 Micron = 1000 NanoMeters

Note the size range of viruses in this chart… .005 – 0.3

The .005 is much smaller than many water filters claim to remove! What is important to remember is the size of viruses that have proven to be harmful or deadly to humans. Smaller viruses exist according to scientists, but whether they are a risk to mankind or not, has yet to be determined —- it is also important to differentiate between water borne viruses and air borne (which can be much smaller).

Water Filters like the Lifesaver Jerrycan will filter out viruses to 0.015 microns (15 nanometers) in size, which includes all of the most common viruses found in water. Amazing technology when you think about it, a portable water filter that can remove such microscopic (and dangerous) particles from water.

Relative Sizes of Particles and Comparison of Dimensional Units

1 micron is a millionth of a meter or 1 inch divided into 25,400 parts.

Substance Micro-meters (microns)
90% of Wood smoke particles are smaller than 1 micron
Bacteria (average) 2
Red Blood Cell 8
Talcum Powder 10
White Blood Cell 25
Human Hair 70
Grain of Table Salt 100

Particulate pollution in the past decade has been measured as PM10, that is particulate matter 10 microns in diameter or less, which is talcum powder size. Recently the focus has shifted to smaller diameter particles, PM2.5, which denotes all particles 2.5 microns and smaller (bacteria sized). These small sizes are thought to be more injurious because they are deeply respirable, becoming lodged in the farthest recesses of the lungs. Smoke from wood combustion is almost entirely in this range.


So now what size fines are your wanting to filter?

Here's something also to consider.

The diameter of a Human Hair is 100 microns.

The Human eye can detect a particle larger than 50 microns.

When you brew coffee or tea, in a paper filter bag, the bag filters out 10-20 micron or larger particles.

As said previously, I'm getting lots of solids being deposited on the lettuce roots, and settling on the bottom of the DWC trough. I have no idea what micron they are. I just know that the RFF is not removing enough of the solids.
Thanks for the lesson in particle size.

I think a static upflow filter (SUF) or similar would probably be a good idea - it sounds like you're getting a lot of solids that won't settle out, i.e. they're light enough that they just flow along with the water even when it's moving very slowly. The size of the particles isn't relevant in this situation; small particles can be dense enough to settle out and large particles can be light enough not to. (Or they do settle out, they just take long enough to do it that they make it through the RFF and into your DWC!)

I'm partway through building one myself because although my RFF does get most of the solids, there's enough going through to my sump that I want to reduce it. Cleaning out a filter is going to be easier than cleaning out my sump, and won't disturb the yabbies!

I am a bit out in left field here with small setups like you show.
My preference is to fill drum/half drum with media and find that is a much more effective filter.
Lot more KISS as well. Improved if you have a mesh false floor / gap at bottom.

Basically feed water to the bottom of the media and then an overflow at top to DWC.
Have a ball valve at bottom and just drain it every now and again as needed.
Seems to work very well. I just see RFF, SUF etc as unnecessary effort at that scale.
(you do those if your fish stocking and species really needs it)

Thanks dlf_perth.
I like the idea of the mediabed, but how would I stop the media blocking the drain in the bottom?

>> I like the idea of the mediabed, but how would I stop the media blocking the drain in the bottom?

I run 50mm or 90mm pipe with lots of holes drilled in it across the bottom connected to the outlet. It sucks the crud through no problem as long as the holes are as large as you can make them for your media size. You could put larger rock at the bottom for first 100-200mm or so.

Else put in a false floor using plastic mesh/grid (eg a plastic sieve or bread crate depending on your media).


both methods work. The false floor is more effective as the crud stays in the bottom and is easier to flush out.

the added benefit is you get additional biofiltration since the nitrifying bacteria establish in there as well.
Whatever I flush out (usually bucket or couple) I put on my citrus trees and wicking beds.


p.s. I missed this from earlier post at top of the page...

[DLF] I also take the return water from the bottom of the DWC. Helps to circulate and keep the DWC clean.
[Farmz] Not sure I understand what you mean here.

basically in the DWC I run the outflow from a pipe that lays along the bottom of the DWC like a SLO rather than taking water from the top. The same effect can be done using something like a siphon bell but with a hole in it so you don't get a siphon (ie. water is pulled up from the bottom and the suction takes away some of the crud that tends to accumulate on the floor of the DWC).

Ok. Things to think about.
Thanks.

Yeah I eventually worked out what you meant re the SLO in the DWC trough, which I did.
Thanks again.