Week 136 Update: *Notes in the comments*

Here is a system breakdown:
Sand
One of the beds uses sand that is used underneath synthetic turf, it is sized at .2mm to 1mm and is not recommended. The other bed uses a coarse sand, used for underneath pavers, it is sized at .4 to 1.2mm and is highly recommended.
Water
From November 2023 to June 14 2024, our daily water use was only 0.01% per day due to the fact the our grow beds were not covered, and we had fairly consistent rain over those months.
pH
We check it 3 times a week but after this system matured (in about 5 weeks) the pH never changes and stays at 6.4.
TAN
We check it 3 times a week but it has never been an issue.
Fish Food
We use properly formulated commercial feeds of floating pellets and feed the fish twice a day to satiation. It costs $15 a kilo (we plan on getting it in bulk to bring the cost down)
Fish
This system was meant to be temporary and so it ran on about 10 goldfish until April 2024 when we replaced them with 118 jade perch fingerlings.
Air Pump
We have an air pump with built in battery backup in case of power and/or water pump failure. It is 12 watts and it runs 24 hours per day.
Water Pump
Our water pump has a digital controller to set the flow rate. It currently runs at 12 watts for a total of 2 hours per day and is a DC pump so we can connect it to solar.
Timer
A mechanical electrical timer is used to set the irrigation schedule for the water pump.
Irrigation
The grow beds are irrigated for 15-20 minutes (until the sand is saturated) every 2 hours during the day, there is no irrigation at night. Each irrigation cycle should pump 25% of the volume of the fish tank.
Fish Tank
1000L in a catenary shape, lined with a food safe EPDM liner.
Heater
We added a 50W heater for the months of June and July as it is too cold for the fish. It runs 24 hours per day.
Grow Beds
2.4m x 1.2m and 30cm deep. Sloped 5 cm towards the drain.
Diary
We keep a diary to record our observations and track pH and TAN tests, daily temperatures, feeding rates and any other notes.
Plumbing
Some hoses to irrigate the water, 2 valves to set the flow rate for each bed, and a puddle flange for a drain on each bed.
Costs
With Australian electricity priced at about 30c a kilowatt, this system costs $3.17 per day, or $13.60 a month.
We are looking for a better supplier of fish food, we are currently paying $15 a kilo, we will calculate the costs and update this soon.....
Solar
We are in the process of setting this up and will update with all the details when we can.
Bell Syphon? No!
There is no syphon at all.
Extra Filtration? No!
There is no extra filtration.
Supplements? No!
There are no supplements.
We learned about this from www.iAVs.info

[@iAVs-Sandponics]

Despite the relentless rain and our hectic schedule, we managed to make some progress on our tomato garden.
To ensure the safety of our crop, we diligently covered the plants with bird netting. However, we soon realized that leaving the netting on throughout the day could lead to fungal issues, especially given the constant rain and high humidity.
To combat this, we developed a routine of removing the netting during daylight hours, allowing for adequate airflow and reducing the risk of fungal growth.
Of course, this daily ritual of removing and replacing the netting came with its own set of challenges. Inevitably, some tomatoes would accidentally be knocked off the plants during the process.
But, as the saying goes, "When life gives you fallen tomatoes, make fried green tomatoes!" We happily sliced up these unintended harvests and enjoyed them as a delicious, crispy treat.
In the video, you'll also notice that we made the strategic decision to remove some of the smaller tomatoes from the plants. This technique, known as "thinning," allows the remaining tomatoes to receive more nutrients and energy from the plant, ultimately leading to faster ripening and a more bountiful harvest.
Temperatures have now decreased to a low of 13 degrees Celsius, causing the jade perch to reduce their food intake by more than half. Consequently, I have installed a 50W aquarium heater that operates continuously, maintaining a temperature of 18 degrees Celsius. This adjustment has led to the jade perch resuming their normal eating habits.
The updated weekly expenses, calculated at a rate of 30 cents per kilowatt, amount to $2.50 for the heater. The water pump, currently running at 17 watts for a total of 2 hours per day, costs approximately 8 cents. Additionally, the air pump, which runs constantly at 12 watts, incurs a cost of around 60 cents. The fish feed, priced at $15 per kilogram, results in an expense of $5.20.
Therefore, the total weekly operating cost is $8.40.
This week's harvest yielded approximately 470 grams of spinach, 1040 grams of tomatoes, and a small handful of snow peas.
Going by standard grocery store prices in Australia the snow peas are worth $2.70 ($27p/k) the roma tomatoes worth $17 ($16.50p/kg) and the spinach is worth $7.99 ($17p/kg) A total of $28.69 minus expenses equals a 'profit' of $20.29. Purchasing fish feed in bulk would lower the cost of feed to $10 per kilogram, resulting in a 'profit' of $21.69.
The prices mentioned above would increase significantly if organic prices were used. This calculation also does not account for the fact that the fish will eventually be harvested, or the time and energy saved by not having to make trips to the store. Nor does it take into consideration the satisfaction and enjoyment derived from operating this system.
With an FCR of 1:1, the feed, and therefore the fish gain this week would be 116 grams.
No additional supplements are used, except for a foliar spray to combat fungal issues caused by excessive rainfall and cloudy weather. The pH levels are monitored every few days, but have remained stable at 6.4 for over 18 months, requiring no adjustments.