Backyard Aquaponics
A place to discuss aquaponics

Cool, i just got a new way to explain my system..........entropy natural movement towards chaos / disorder

Ah Steve, you don't need fancy words, all you need is a bit of quality time to work on your system...think there might be a few others in a similar situation

When I was a kid (baaaaaa) I watched my dad drill wells.
I'm going to have 16 yards of gravel to wash in a month or two. So, it seems to me that I could dig two pits put out a tarp using a 1800 GPM pump just spray wash the gravel letting the water flow into the pits where the heavy stuff would settle out; pumping the water off the top of the second pit; perhaps plastic lined.

With the hot/dry we get here in summer the gravel is still covered in dust, which is the main problem in systems. and does not all come off ie its somehow attached. If it wasn't you could just get a garden blower and blow it off.

Thought about a barrel with water and a shallow laundry basket (Scott). Fill with gravel suspend in the water, pump compressed air in the bottom of the barrel and cleaned. Even if you introduce floc into the water the second time you do it the gravel will get coated because the mechanical action of the compressed air will put it into suspension again (I think).

With floc, you allow to settle, decant water and re-use. I think most flocs are non toxic and generally breakdown with exposure

It appears that dust attaches to gravel by what is called the van der Waals effect. This unfortunately encompasses various low strength bonding mechanisms. The most likely explanation is in our case, when the gravel is dry, is electrostatic action in that gravel is a non conductor and the particles are negatively and positively charged.

This is difficult in that to overcome the bonds would require some way of ensuring that the gravel and dust are for the most part either positively or negatively charged.
That is they would repel each other. Ionised gas or some other way of altering the electrostatic charge is likely beyond the average hobbyist.
There is another problem in that if it could be done the resultant dust, which is likely to be made of silica particles would be highly injurious to human lungs.
Looks likely we stick with washing although Bazz suggestion of a flocculant may provide few new ideas. If we take the reverse of this and use a deflocculant i.e. something to keep the fine particles in suspension they are unlikely to restick to the gravel. Flocculation/ deflocculation is the water equivalent of providing positive or negative charges (Sort of). Will check this out when I have time.

If there are any scientists out there, this needs checking, I ain’t one.

Sea water is a good flocculant - just look at the dirty rivers where they meet the sea. The Yarra here in melbourne is ultra muddy, and yet clear well before it reaches the coast, - as soon as it becomes brackish in fact.

However freshwater fish don't appreciate the sodium chloride so much, and even if you had brim or salmon, the plants'll hate it, so you'll probably want to wash the salt off after :-) Heh! Double washing - there's a concept to save us time

There are anionic and cationic flocs, so depending on the pH of your water, either one can be used. Lime also makes a reasonable floc at highish pH

We have a really excellent river at the bottom of our property - very clean - and it has very nice sized river rock, gravel, sand. I assume the easiest thing is to bring down to screens - large to exclude big, small to get rid of sand.

I will mount in the river and just throw the stuff in it, and let it accumulate in a bucket which will then be empty in a container.

If I mount the coarse above and use the finer one under it like a funnel, I should only have to throw the gravel mix once. If I do it with running water - it is assumed all washing is finished.

You do realize when I say "I", I mean one of my workers... This sounds like work!

The river is the perfect temperature for swimming - sounds like a gravel washing party to me!

Am I being excruciatingly lazy by just filling the GBs without washing the hydrotron , then filling with water and letting a 500 L/hour canister filter suck all the water through for a couple days & collect all of it in the filter pads ?

My 3 koi didnt seem to mind , the hardest part was cleaning the filter pads in the canister filter twice a day . I imagine it'd be easier with one of those monster canisters that Ive seen at the lfs

no boris not lazy, just utlising what you have available to you

I had another go with my laundry basket in the mixer.
Worked a treat

Ingredients
3/4 Tonne of 14mm gravel (blue metal aka "screenings")
1 x cement mixer
1 x plastic laundry basket ( with extra holes drilled in base)
1 x large umbrella (optional)
maybe 150L of water?
Beer and loud music.!

Method
Place basket in Mixer
Load basket with 5 shovels of gravel
Run mixer (dry) for 1 minute
continue to run mixer while rinsing with water from hose for 1 minute.
Lift basket of clean gravel from mixer an pour into growbed.
Empty mixer of water and silt.
Sip beer
Repeat above for about and hour and a half.

Luv it Scottt

brilliant idea Scottt

we just re-commissioned one of the duckweed baths as a gravel growbed. I got some gravel, that due to the 500mm of rain we've had recently was fairly clean. We just filled the bath up with gravel, disconnected the drain from heading to the sump, put a plug in the drain and filled the bath with water. the first time the water was pretty silty. This water got drained out to waste.
I then filled the bath again and left it to sit for an hour. That water ran to waste too, not much silt or sand in it.
That was it. The system is running clear.

[quote=scott]I had another go with my laundry basket in the mixer.
Worked a treat Very Happy [/quote]

How long did the laundry basket last?
How full did you fill it with gravel?
In bathroom / laundry usage they usually fail miserably after 3 - 6 months.

Regards,
Tony