Water Bio Filter - sand filter

[stevo]

I came across these things on the net today, I thought it might help with keeping my pond water clean. At the moment I just have a general pond pump which just basicly circulates water. It has a foam filter on it but I think it'd only stop logs and large fish. I haven't seen these mentioned before when looking at aquaculture before so maybe there's a reason, who knows, i'll have to do some more research, and then make one anyway.

These seemed to be mainly talked about for use in third world countries for providing cleaner water. I don't think they stop micro organisms from getting through and you still get sick from the water? ... but I don't plan on drinking my pond water, just keeping it cleaner.

 

[stevo]

more research and I see aquaculture people using coarser materials like gravel / rocks, probably for faster flow... hrm....

maybe this needs to go in to the Aquaculture section?

 

[Steve]

I know Bear Grills (survival expert) says that if you find water that is running though soil or earth then it is normally filtered enough to drink.
I'm sure there are some caveats but apparently sand/dirt etc is fantastic at filtering out nasties.
You might be onto something. Looks simple enough to make too.

 

[Mark]

But isn't this what happens with an aquaculture setup anyway where the water from the pond is filtered through the garden bed and back into the pond?

Could you possibly combine your proposed filtering method with a small raised garden bed and grow some greens at the same time?

maybe this needs to go in to the Aquaculture section?

Ok, I'll put it in the aqua section then

 

[stevo]

Mark, do you mean aquaponics?

But, good ideas there. I have set up a very basic filter system and put some water plants in.

This is a test system, if it works i might set up something more permanent and more attractive.

1. I used a plastic tub that i already had. - free
2. the water flow comes in at the top
3. there's two buckets of small gravel as a basic filter - $6
4. offcuts of some 50mm ag pipe curled around the bottom of the tub and directed in to the outlet
5. water tank outlet fitting - 72cents - (worth $15 - funny story there)
6. water outlet is installed at the bottom of the tub, so the water enters at the top surface and filters through the gravel.

I would like to add some smaller gravel or sand to create a better filter.

 

[Mark]

Oh yeah I meant aquaponics NOT aquaculture (I had been watching a report about the rise of Tasmanian salmon aquaculture and it was stuck in my head)

That's a really inventive filtering solution. I would never have thought of that!

 

[stevo]

Could you possibly combine your proposed filtering method with a small raised garden bed and grow some greens at the same time?

you got me thinking about this, so yeah maybe if i raise the gravel level i can grow things like lettuce? Apparently aquaponics has some complex stuff with bacteria, you have to achieve and maintain some kind of bacteria in your grow media, i'm not sure if i want to try that yet, but i guess if i make this filter structure i can always change it to aquaponics later if desired.

 

[Mark]

you got me thinking about this, so yeah maybe if i raise the gravel level i can grow things like lettuce? Apparently aquaponics has some complex stuff with bacteria, you have to achieve and maintain some kind of bacteria in your grow media, i'm not sure if i want to try that yet, but i guess if i make this filter structure i can always change it to aquaponics later if desired.

I don't know about the bacteria (although I do vaguely remember reading about it) but my gut feeling is salad crops like lettuce, endive, even bok choy, would grow reasonably well in a gravel mix/filtering setup - if the water needs filtering then there must be a collection of some nutrient rich composting material in there. I think there would be enough nutrients to sustain the plants. I often get salad plants popping up in my gravel path and it's laid on top of salty sand God knows how they survive!

 

[stevo]

My dodgy test filter tub has been running for a couple of weeks now, and seems to be a success. It's collected a heap of crap from the pond, but now the gravel is full of crap which itself needs to be cleaned? ... but atleast that's the idea.

The pond water is now really clear! no algae!

Out of interest I planted a Water Cress plant in the gravel and it's going well and spreading. In the last few days I put a small lettuce in the gravel and it seems ok, it hasn't died atleast. Looks like I have aquaponics, even if on a micro scale?

So, I might plan a little aquaponics trough/water filter, basicly the same as the tub pictured above but a bit more incorporated in to the pond design structure.

 

[Mark]

Well that's a great outcome

So it's working well to clean the pond but the issue is the build up of the muck in the filter. Here's a few ideas - you could use a straining basket of some kind instead of a medium and that would be easy to empty into the garden - that's if you didn't want a mini aquaponics on the side. Or, make the aquaponic filter bed larger so it takes longer to fill and gives a chance to grow crops in it with a view to empty it out once a year or so?

 

[stevo]

yeah Mark, i thinking maybe a two stage filter, like a fine filter first to strain the solids, then the gravel can hold the plants and draw the nutrients out of the water. We're probably trying to re-invet aquaponics and they know all this stff, i'm too lazy to research, or i just like to muck around with this stuff.

I put a big sponge under the water inlet and it's been collecting a bit of stuff which is good, so i just need to improve on that.

The plants are looking healthy....

 

[Mark]

It looks a treat really! I mean it's doing the job and providing you with some salad grown with free fertiliser and you don't have to water it daily. The water looks nice and clean too.