Backyard Aquaponics
A place to discuss aquaponics

I'm calling this experiment my Sandpit System as it took over the kid's sandpit which was already taken over by the dog. So I evicted the dog, got rid of the sand, cut back the overhanging tree and plonked in some fish and seedlings.

The tank is a 500L 'pond'.
I run one pond pump 24/7 through a pond filter with UV light back into the pond with a venturi on the end. This pump also has a foam fish filter on the intake.

The 'growbed' is a hydroponic 8 pot dual trough with frame.
The pots are filled with expanded clay, about 150L worth. They are covered with white shadecloth. I run another pond pump on a 15min in the hour timer up to the pots. The pots are not flood and drain or loop syphoned or anything else, just straight flowthrough then returned to the pond.

I initially put in 10 goldfish (only 6 survived the shakey sun baked child handled transportation) whist deciding on the type of growbed and frame to use. They saw through the lack of filtration and the pea soup episodes. Just before new year I added 20 baby silver perch into the mix. So far I've only had one silver unexplicably go belly up. I intend to only have 20 full sized fish in the pond in 12 months time as 20 silvers in 500L is around about the theoretical aquaculture limit. I get my feed from the BYAP store and chuck it in bit at a time twice a day watching for when the fish stop taking the food.

So at the 4 month mark, 6 goldfish and 19 silvers are growing, feeding and behaving well. pH has gone from a steady 7.8 to 6.0 and correspondingly the plant growth has responded very well. EC is at 1.5. Ammonia is low, Nitrite is low and Nitrates are at 40ppm.

Battery backup air supply is still on the to-get list. And yes I already have a bigger system in mind.

Setting this up has come after lots of reading, especially from this forum, so a big thanks to existing members who have shared their knowledge. So far my young family and I have thoroughly enjoyed watching the system mature. This is turning into a very satisfying pastime (addiction?).

My Sandpit System

If you can leave the uv light off because they say it will kill the bacteria you need in aquaponiics

nice sized system. are you going to do any more beds?
and whats the larger system in mind going to be?

Although I hear stuff like this all the time, i'm not sure how it can be true. these filters are designed to provide a home for nitrifying bacteria, just like our growbeds do, so surely if the UV is good in aquaria, then its at least not detrimental to AP? According to my microbiology, the bacteria are in the filter media, not the water (otherwise we wouldn't need any filter media, the water would be enough), so passing the water through a UV clarifier just helps kill off algae and other stuff (that actually lives in the water) that would otherwise make a mess of the system (and make it hard to see the fishies).

or am I missing something?

I've never used the uv light. For an extra $20 I thought I'd get the filter that had the inline light... just in case. They are more expensive on their own and form an integral part of lots of aquaculture setups. But I really wanted to try the system without using it first. So far so good.

Thanks mate. I find it not too big or ugly that it'll upset the boss and big enough to get a handle on the whole aquaponics thingy.


As for a larger system I have two in mind. Haha

System 1 - Double Sandpit
Another 500L tank, divided somehow roughly 150L/350L so as to have the ability to stage the fish and keep a more consistent nutrient level. Fingerlings in the 150L, then at 4 months move them to the 350L, then at 8 months move them to the 500L, then at 12 months yum yum. Each 4 months getting new fingerlings. All figures are rough but you get the idea. Obviously species and temperature fluctuations are major considerations.
There are a couple of different hydroponic pot systems out there and I'd extend them out to take up the extra nutrients.

System 2 - Two Family System
I have a mate who is threatening to erect a 100m2 greenhouse tunnel and we have ideas of putting in a 9000L system loosly based on the Double Sandpit idea. My calcs suggest that we can raise 360 fish (silver perch) a year by stocking 120 at a time, 4 months apart, in 1K, 3K, and 5K tanks. That's 3.5 fish a week per family. Then whatever edible plants can be grown from that are a stellar bonus.

Time will tell. Dreaming (and planning) is fun though.

OK, time for a long overdue update.
Have been taking photos, meaning to transfer to pc, then lost the transfer cable. I have aquired a new cable now so time to upload those snaps.

These were taken mid April, show the tomatoes starting to get going, the white shadecloth cover and an example of my engineering prowess (notice hinged lid of the tank cover cannot open fully because it is under the tray ).

Here are a couple of hardware shots.

A couple of plant growth shots.

My first tomato and the food I'm using.

This next lot are from one month later, mid May.

It had still been pretty warm through late April and early May, the fish had been feeding well and the plants just took off.

Cleaning day!

I want that uneaten food out of the tank. Crap from the pots also builds up in the corners. My 'vacuum' is the spare pump. I push the hose on the end of a stick around the pond sucking up the water using my spare pump, through the swirl filter then through a t-shirt filter, back to the tank. The swirl filter doesn't have much of a chance to work because the water flows too quickly through it, I think. It does pick up a bit of stuff, but the t-shirt is filthy. Yuk. The silvers are really curious during the whole process and follow the end of the hose around. Haven't sucked one up yet.

Feeding started to slow down due to the drop in weather and started to notice non optimum conditions with the plants.

The chives are starting to look a little old and the tomatoes started to get an infection of some sort. Also the bugs have found my system. Picking the buggers and feeding them to the fish is the order of the day.

Also cleaned the pot tray and discovered serious root growth from the tomato plant. Kind of cool.

Have you had any issues with the feed tubes to the pots blocking up?

Also, please make sure your pH is really only just down to 6. If you are running the API freshwater master test kit to read your pH I believe it only goes down to 6. If it reads 6 the pH could actually be much lower and without any sort of pH buffer in the system, it is possible to have a crash (basically the pH can get too low and the bacteria quit converting the ammonia and you suddenly have ammonia spikes.)

It isn't that systems can't operate below 6, ya just want to make sure it doesn't so acidic that things go wrong.

Looking good by the way