7-Aquaponics

Aquaponic system

Aquaculture ( it helps the fish to grow) + Hydroponics (it helps the plants to grow)

Grow Bed

At least 12″ (30 cm) deep to allow for growing the widest variety of plants and to provide complete filtration. (Must be made of food safe materials and should not alter the pH of your system, beware of concrete)

Fish tank

250 gallon (1000 liters) or larger seems to create the most stable aquaponics system. [m3=1000 liters] Larger volumes are better for beginners because they allow more room for error; things happen more slowly at larger volumes. (Must be made of food safe materials and should not alter the pH of your system, beware of concrete, for example).

The length to width to depth ratio should be 30:3:1 for good flow patterns.

Rule of Thumb

• 1 pound of fish per 5-7 gallons of tank water (0.5 kg per 20-26 liters) - When your fish are young and small, reduce the number of plants in proportion to the size of the fish and their corresponding feed rate / waste production.

20kg fish for 1000 liter tank

• 1 lb (0.5 kg) of fish for every 1 sq ft (0.1 sq m) of grow bed surface area, assuming the beds are at least 12″ (30 cm) deep.

4sq m for 20kg fish

Growbed Medium

LECA (Lightweight Expanded Clay Aggregate, AKA Hydroton), Lava Rock, and

Gravel are the most widely used media types. If you choose gravel, understand it’s source and avoid limestone and marble as they could affect your pH.

Water Flow

You should flood, then drain your grow beds. The draining action pulls oxygen through the grow beds.

The least complicated way to achieve a reliable flood drain system is using a timer. While more complex, siphons are also excellent options for aquaponics. 

If you are operating your system with a timer you should run it for 15 minutes on, and 45 minutes off. You want to flow the entire volume of your fish tank through your grow beds every hour if possible. Therefore, if you are running your pump for 15 minutes every hour (see above), and you have a 250 gallon/1000 liter tank, you need at least a 1000 gallon(gph) /4000 liter per hour pump.

First Cycle

• Fishless Cycling is recommended because it will develop a robust bacteria base and allow you to fully stock your fish tank in a couple of weeks vs. the traditional method of using fish which takes over a month and is very stressful for the fish.
• Add plants as soon as you start cycling your system, but accept that they may not grow well for the few weeks required for cycling to occur.
• Add fish once nitrates are present and the ammonia and nitrite levels have peaked and declined below 1.0 ppm.
• Add a handful of composting red worms to each grow bed once your system is fully cycled and fish have been added.

Feeding

• You may feed as much as your fish will eat in 5 minutes, 1to3 times per day. An adult fish will eat approximately 1% of its bodyweight per day. Fish babies will eat as much as 7%. Be careful not to over feed your fish.
• If your fish aren’t eating they are probably stressed, outside of their optimal temperature range, or they don’t have enough oxygen.

Check List

• Ammonia and Nitrite levels should be less than .75 ppm (If either of the above circumstances occur, stop feeding your fish until the levels stabilize, and, in extreme cases, do a 1/3 water exchange to dilute the existing solution.)
• Be sure there is plenty of oxygen in your fish tank, if you don’t have enough oxygen being infused into your tank your fish will be gasping for air at the water surface. (You can increase oxygen flow through the use of a separate aeration device and by diverting part of the water from flooding and draining your grow beds directly into your fish tank.)
• Avoid adding anything to your system containing sodium as it will build-up over time and is harmful to plants. Do not use citric acid as this is anti-bacterial and will kill the bacteria in your bio-filter.

pH

• Target a pH of neutral, or 7.0, in your aquaponic system. 

This is a compromise between the optimal ranges of the fish, the plants, and the bacteria.

For fish, this is a pH of around 6.5 to 8.0

For plants, this is a pH of around 5.0 to 7.0 

For bacteria it is a pH of 6.0 to 8.0.

• Test pH at least weekly, and as frequently as 3 – 4 times per week, using your Freshwater Master Test Kit.
• During cycling pH will tend to rise. After cycling your systems, pH will probably drop below 7.0 on a regular basis and require being buffered up.

Best method for raising (buffering) pH if it drops below 6.6

Calcium hydroxide – ‘hydrated lime’ or ‘builder’s lime’.

Potassium carbonate (or bicarbonate) or potassium hydroxide (‘pearlash’ or ‘potash’)

[If possible, alternate between these two each time your system needs the pH raised. These also add calcium and potassium, which your plants will appreciate.]

While they work, be cautious about using natural Calcium Carbonate products (egg shells, snail shells, sea shells). They don’t do any harm, but they take a long time to dissolve and affect the pH. So, you add it, check pH two hours later and nothing has changed, so you add more. Then suddenly, the pH spikes because you have added so much.

Best methods for lowering pH, in order of preference, if it goes above 7.6

pH Down for Hydroponics- (be careful of using the aquarium version as this has sodium that is unhealthy for plants).

Other hydroponic acids like nitric or phosphoric as the plants can use the nitrate or phosphate produced.

Tips

• Washbasin around is a nice to have to wash produce, nets, test equipment, and most importantly, your hands.
• Nearby access to fresh water required as your system will regularly need to be topped off with water due to natural losses through evaporation and transpiration. 
• Proper drainage, easy to clean area
• The risk of accidental electrocution or drowning is real if pets or young children were to be climbing around the system. Tampering with the system could also create other unpleasant conditions such as the death of your fish and plants. You may need to secure your system from natural predators.
• Any tank culture system that relies on continuous aeration or water pumping is at risk of mechanical or electrical failure and major fish mortality. Backup systems are essential.

My plan

bed - 2x0.5meter (0.3 depth) x 4 beds =  4 sq.m

tank - 4x0.5meter x 0.5 height = 1000liter

Water blade fountain

HDPE products are safe and are not known to transmit any chemicals into foods or drinks, making this plastic a low health risk variety, according to Chemical Safety Facts.

https://www.kjasons.com/ponds-and-pools/aqua/557-aquaponics-system-low-cost-fish-farming-kerala-india.html

https://www.kjasons.com/ponds-and-pools/aqua/518-aquaponics-designing-and-installation.html

https://www.kjasons.com/ponds-and-pools/koi-ponds/578-water-blade-fountain-for-pools-and-ponds-india.html