Backyard Aquaponics
A place to discuss aquaponics

The initial washing isnt a waste of time, i think its very neccessary.
I filled a 1.4 cubic metre bed with scoria, i tried to wash the first part, but didnt work well, so i just dumped it in the bed and did a few flood and dumps to get rid of much as possible, i have since pulled all of that out and found a layer on the bottom, very small rocks and scoria dust so well settled amongst the bottom 2 layers of scoria (25-30mm pieces) that it was like digging through concrete, i needed to blast it apart with a large capacity pump.
I since used that same bed to simply flood and sieve (simply fill the bed well above media level and use a large sieve to scoop the rocks out) another cubic metre on top, when i threw them into the new biofilter there was only trace amounts of fine dust.

TL;DR: wash your scoria properly by flooding a bed and moving rock to another bed. its quite neccessary.

Hi Yavimaya
I have come to the same conclusion as I've found a thick sediment layer halfway down one of the beds, I havnt checked all of them but have been procrastinating about re doing the bed that hasnt struck any seeds. (very old test stock)
Both the sumps have a thick layer of dust in the bottom that I'm waiting to do a water change and syphon it all out.
The water is actually pretty near crystal clear now and I can see the bottom of the IBC, it took about three weeks to clear.
Once I have everything nice and tidy I will have a look at doing each bed one at a time as they become denuded of plants.
I suppose the anaerobic areas could be de-nitraters.

I suppose the anaerobic areas could be de-nitraters.

Or a potential time bomb,don’t risk it.

Hi Dasboot,
I should have added a grinner there, sorry.
I have had a very badly anaerobic section in a large aquarium when I was experimenting with mixing pottery clay, blood and bone and chelated iron into balls and burying then in the sand.
When I serviced the tank 18 months later they were still there but jet black inside and stank of sulphides. Never lost any fish from it though, the Kribs kept breeding.
I think the time bomb will go off when you disturb it so it will have to be done before it occurs.

This is how I cleaned my scoria with a sieve and you can see the amount of fines that I cleaned out of it. That is from one 2.4x1.2x0.35m bed and 8 half barrels worth of of scoria.

The pile of fines is about 100 deep and tapered out beyond the tressel legs.

I've had a look around but still cannot make up my mind.
Is this iron deficiency on my climbing spinach or magnesium?

The bok choy shows no sign of a deficiency. (nor do any of the other plants)

pH 6.5, Nitrites 0, ammonia 0, nitrates dropping to 5.
I'm assuming from the galloping bok choy and with just the fry food that the plants have used all the nitrates up from the cycled charlie carp. does this sound correct?

I am still unsure why the spinach looks like it does, in all other respects its growing very well and quite fast. (no previous experience to compare it though)
Pulled the first batch of bok choy, lovely, crisp, sweet, no trace of bitterness.
A quick note on nitrate tests.
I have been using an old test kit of X years of age, tthis was giving reading between 40 down to 5, I thought a sudden drop to 5 a bit suspicious so re tested, yep, only 5ppm nitrate so I used another test kit not so old but not new, hmmm, nitrates back up to 40ppm. I'm more inclined to trust the youngest kit bit wonder how old before they become unreliable or are they all unreliable and you hope for the best.

AAAARRRRRGGGGGGHHHHHH!!!!!!!!!!!!!!
Some kind of four legged critter has decimated my egg plants in the dirt garden and the melons in the aquaponics garden.
The fruits have been eaten out still on the plant.
Rats or possums I suppose.



I'm loathe to set rat traps in case I catch a possum although I'm feeling very vindictive at the moment and I dont want rat poison anywhere near the aquaponics.

On a different note I am gob smacked at the speed of growth of both plants and fish
A nice feed of bok choy

After harvesting spinach and various choys

then 5 days later the new bok choy seedlings in the front bed have more than doubled in size.

Help, I want to expand

You've got a nice system going, what do you want help with?

Thanks, the help was just an exclamation, I have caught the bug and want to go bigger but the minister for war and finance wants to wait, probably the wisest decision and get a full season under the belt.

quick update, the three/four days of heavy rain overflowed the sumps twice.
I had to release a fair bit of water to get the siphons working correctly again.
The biggest surprise was the drop in ph, it has been stable since christmas at 6.5 but after the rain it had dropped to 5.0 ouch.
I'm slowly pushing it back with touches of potassium bicarbonate and calcium hydroxide.
I still cannot believe how much green stuff weve eaten from this small footprint and the fish are growing very fast.

After eating the last of the veggies in one of the barrels I decided to wash the sand out.

This bed was washed pretty well when I first started with the pressure hose so I thought it would be ok.
This is the load of sand from that one barrel.

There were no anaerobic areas but I know there is more sand in some of the other barrels.
It was washed a bit at a time in the wheelbarrow full of water with a sieve as put forward by another member and was rather back breaking, just another seven to do.

Slowly expanding, added another grow bed. At the moment the undertank is acting just as a sump, a SLO feeds from this to the sump under the next growbed bank.


After cleaning out a heap of fish poo from the distribution pipe I decided to add a radial filter in an effort to minimise this and get some fertilizer for the dirt garden


it seems to be working very well. The pipe work is a bit cramped but is still gravity fed.

Its a bit cramped and sits on a pile of bricks to get the height correct.

I can still sit the barrel higher if I find it filling too high but that will add more bends in the pipe work.
Plant wise we've decimated the bok and pak choy, the choy sum, all the mustard greens and cos lettuces so they have just been re sown, there is water cress, kang kong, snow peas, tomatoes (just heavily pruned) cabbage (never again, it takes over) beetroot (crowded out by the cabbage) and one lettuce left.

We were very heavily hit by caterpillars of some kind but 3 weekly applications of dipel wiped them out completely with little loss of crops.
The Lebanese cucumbers went beserk but also smothered with aphids that I couldnt get under control and as the aphids started spreading to some of he other plants I pulled out the cucumbers. I will try them again in the dirt garden where I can use pyrethrum.
You can see the netting roof bowing from 25 meters of 25mm black poly used as a solar water heater, fed by the smallest aquarium pump I could find. Its not very effective at the moment as the water flow is still to fast to warm up by much, half to one degree C only but its a worth while experiment and I will be using 75 meters on the shed roof now I know it works.
The fish are growing well, approx the size of my open hand but extremely skittish, I think come harvest I will use a rod and line.