Backyard Aquaponics
A place to discuss aquaponics

Hey guys:

I am sure that somewhere on the forum someone has put out information on how to build a cheap filter for NFT systems. Yet, I thought I would put on a description of what I did.

I simply took a 5 gallon bucket filled it from the bottom up with 3/4" gravel, 1/8" pea gravel and a layer of sand. Each layer is 1/4 of the bucket volume. The last quarter is water. It was amazing how it immediately got the water clean and the plant root were cleared of their scum.

You see by the pictures that I cover the bucket because of algae. However, its white color still promotes algae. I may have to cover the outside to kill off the algae.

Here are some pics.

So simple, top job

Thanks for posting this Filter. It's a good idea to keep in mind for a filter. One thing that has occurred to me is the solids. How will this setup deal with the solids? would the entry point of the water to the bottom of the bucket turn anaerobic or does the water flow keep this from happening? is there a top overflow return back to the tank if the filter plugs up for some reason?

I saw this filter on a bigger scale at Growing Power in Milwaukee, WI USA. They said that the top of the sand can be shop vac'd off every so often to remove junk. I believe strange as it may seem the solid actually migrate to the top. Don't quote me on that. It just seems I heard or read something along that line. It seems counter intuitive given the solids are naturally heavier than water.

I don't know if this will encourage anaerobic bacteria or not. Don't have that much knowledge. I added this bucket many weeks after starting my system. The numbers on Amonnia, Nitrite and Nitrate were and still are good. I don't know how to tell if it is becoming anaerobic.

No, I don't have a overflow return, but my system is a CHIFT PIST and so if it became clogged the only catastrophe would be emptying the sump tank. The flow to the NFT is so minimal it would take a long time to overflow. Thanks for mentioning it because when I first thought about the bucket, I placed it almost above my FT. I was thinking at the time of putting a overflow line out that would dump into the FT in case of a problem. Thanks, I think I will add that when I get a chance.

Simple and neat, well done

what is the water flow direction?

I'm trying to figure out a way to incorporate an inline filter into my system as well but want something cheap and low maintenance.

Does the water enter your bucket at the top or in the bottom?

Generally downward... I think it has something to do with gravity...

I would think the water is flowing in from the vertical pipe (right hand side) being released at the bottom of the pale, flowing through the media and exiting the filter via the horizontal pipe (left hand side).

Arbe is right. The water flows down the vertical pipe which is about a half inch from the bottom of the pail. Then it rises gently up through the 3/4", then the 1/8" and finally through the sand. When it is flowing, you can see a little sand churning on the top of the water. As the water rises, it exits on the left and flows by gravity to the NFTs.

I saw the same thing done with a 55 gallon drum at Growing Power. It is less complex than a swirl filter where you have to make a cyclone affect.

It's look like radial flow seperator.
viewtopic.php?f=1&t=11096

So the inlet pipe being under all of that dense sand isn’t causing back pressure? The sand doesn’t get clogged from the bottom?

Raskal311:

I would guess the weight of the water in the pail causes more back pressure. Remember the pail has three layers that the pipe extends to down through. The top layer is sand, middle 1/8" and the bottom 3/4". The 3/4" has enough gaps that I don't thing it would clog. In my system, this pail is raise about 8' above the sump pump. I have a check valve that keeps water from flowing backwords and draining the pipes completely. However, the pipes get drained some. Why I am telling you this is that if the pipe in the pail has any back flow/siphon it would tend to draw in material. However, it doesn't seem to be drawing in the 3/4" rock.

Long answer to your short question.