This is how I build the frame for the deep water culture (DWC) unit for my aquaponics system.
One thing I learned when working with varnish is I need a lot of thinner to dilute the varnish. The way I do it is by pouring some varnish into paint tray, mixed with some thinner, and paint a thin layer on the wood. However thinner evaporate quickly and the varnish eventually become thicker again, so I have to regularly add thinner to the varnish.
Not an easy task to do, some of the wood are bending so need to use more force to screw at the right place. Some are hard wood, so when I drilled it continuously, the drill bit become too hot and break eventually. If I use small drill bit size, it’s harder to screw, and some screws couldn’t go in, I had to cut them and replace with nails.
Continuation from the previous materials list. These remaining materials were ordered online since I couldn’t find them sold here, and I simply don’t have time to go around the city to look for shop that sell them.
System cycle is a process to be performed on new system, to ensure nitrifying bacteria are colonizing the system. I plan to cycle the system using fish, by lowering stocking density and feed rate, then I need to monitor ammonia level daily to ensure it doesn’t exceed dangerous level. This is to ensure enough nitrifying bacteria to grow to convert those ammonia into nitrate, and this process will continue for about one to two months.
Water pH is one of the most important parameter to monitor. Initially, the system water pH will be a bit high (7 – 8 pH), and over time, the pH should fluctuate around 6 – 7 pH. For EC meter, it’s not so useful for aquaponics, but I think perhaps in future I’ll try hydroponics or fertigation, and EC meter is very useful to measure the fertilizer solution.
Other water test kits that will be beneficial to have are dissolved oxygen meter, various nutrient test meter (to test important nutrient such nitrogen, phosphorus, potassium, calcium, magnesium etc.) and thermometer. All these water parameter data will be useful later to analyze effectiveness of the system.
2 weeks ago I ordered a free copy of The Aquaponics God Manual book, where I only need to pay for shipping cost, and yesterday I received not only one, but three (!) copies of the book. You may order yours here.
Since the progress of building the aquaponics is quite slow, so for now I’ll just cover on the materials I’ll be using to build the set & where I got them.
There are a few stuff missing, such as pond liner, garden netting, pipe fittings, electrical wiring & water test kits. Currently it is still in progress so I’ll update when the system is ready for test run.
There are a few factors that attract me into aquaponics, and I like it mostly because of the fact that I can harvest both fishes and vegetables from a single system. When doing conventional farming, I can only do planting, and it requires back-breaking work, from creating the patches, transplanting, fertilizing, weed control, pest control until harvesting. There are a lot of energy and time to put into it, but not enough outcome to be sold commercially.
So for this aquaponics set, I’ve been learning about it for a few months from The School of Aquaponics Youtube channel. In this channel, the instructor focuses a lot on UVI method, where I can summarize it as, to focus on feed to grow area ratio: amount of feed to be given to the fish is 3% of total fish body weight when they are fingerling, up to 60-100g per day per square meter (g/day/m2) of grow area when the fishes are grown up, with optimum fish stocking density of 60 kg per cubic meter of water (kg/m3).
There are a few other types of grow area, such as NFT (nutrient film technique) and media-filled grow bed, but I choose DWC (deep water culture) since it is the easiest to use and results in high yield. This DWC will be 1 feet deep, covered with netting to prevent pest and to reduce pesticide usage, and also for shade from excess sunlight. There are 3 DWC, each has size of 4 ft by 12 ft, and total of 144 ft2 or 13.5 m2. Each DWC will have 2 small air stone to increase dissolved oxygen in the water.
Fish tank that I’ll be using is a 1000 liter PVC tank, with maximum of 200 fishes, and feed rate of 900 g/day (for tilapia). To accomodate this high stocking density, I’ll have two medium size air stone inside it to supply dissolved oxygen. Pressurized water from pump inside the sump tank will be used to create circular flow inside the tank, where solid waste will gather in the middle, and I’ll use solid-lifting-overflow method to suck the waste out of the tank, into the solid filter.
For the solid filter, I’ll use a radial flow filter method, where water will flow upward then directed downward by some barrier which will settle the solid waste at the bottom of the bucket. I’ll add a drainage outlet to clean out the filter, and this waste later will be collected into mineralization tank. Water overflow from the solid filter go to bio filter tank.
This bio filter will serve multiple purpose. Primarily is for bio filtering activity, where bacteria will convert ammonia in the water into nitrate. Another is to further collect fine solid which couldn’t be filtered by solid filter. And lastly as a degassing component, which is to remove excess nitrogen, carbon dioxide or other harmful gas in the water. All these can be achieved by using trickle filter method.
Sump tank is the central, and the lowest point (in term of altitude) in the system, where all the water will be collected and distributed back. Here is where the 2000 liter per hour (L/h) water pump will be located. It also has overflow outlet, because the DWC will be exposed to rain and this allow the excess water to go outside.
Based on the diagram, the pressurized water line will be using ½ inch PVC pipe and gravity-fed water line will be using 2 inch UPVC pipe. I put a split flow from sump tank to fish tank and DWC units, and each inlet has valve for better water flow control and maintenance.
Mineralization tank is the only component that is separated from the system. Here, solid waste from solid filter will be collected here at least once a week, then it will be aerated to release the micronutrients, and then will be put back into the sump tank after 1 or 2 weeks.
For the styrofoam board design, I choose this design because it provides more holes than the simple rectangular design. I’ll have 6 of these styrofoam boards per DWC, so a total maximum of 648 plants can be planted and harvested at a time from this system – way more than what I can achieve when doing soil-based growing.
Regarding the growing schedule, when using soil, I could harvest the veggies after 8 weeks from germination, so by using aquaponics, hopefully I can half the duration, to 4 or 5 weeks. For germination, I plan to sow the seeds using wet tissues inside germination tray for 2 weeks, then transplant them to the DWC and by using sponge to hold it in the board holes – no net pot is used (to save cost).
There are a lot of rooms for improvement to be done, and I’m thinking about automation and operating it off-grid. Later on I plan to get automatic fish feeder, or maybe look into software-based solution using microcontroller such as Arduino or Raspberry Pi to automate the fish feeding process, measure water quality, and also to automate draining solid waste from filter into mineralization tank, and put it back into sump tank. In the future, I’m looking into setting up solar panel and backup battery to power the pumps and also the automation machines used later.