7 Keys to the Perfect Harvest
With aquaponics, we’re already ahead of the game in setting ourselves up for success. However, it’s not quite a set it and forget it enterprise. These are the factors most newcomers miss that lead to less than perfect harvests. Following these 7 keys to the perfect harvest will have your produce looking and tasting better than anyone else’s in town!
1) Water Quality
Water quality is the most important feature to consider when building your aquaponic system. Too much ammonia, too little oxygen, or the wrong temperature or pH will throw your ecosystem out of whack. To avoid this, make sure to monitor your water quality and make adjustments accordingly.
Ammonia, which is produced by fish, is managed by bacteria in your system that convert ammonia to nitrites and nitrites into nitrates which are used by plants. To manage ammonia, base your population density of fish on your bacteria levels. The more bacteria your system can host, the more fish you can stock. To maximize bacteria, maximize the biological surface area of your system. The easiest way to do this is with media like expanded shale or clay, which can serve the double purpose of stabilizing your plants. You can also build a variety of biofilters that can increase surface area as well. These filters use plastic medias like BioBalls or Kaldness media to drastically increase your biological surface area.
Dissolved oxygen (DO) is critical for the health of your fish, plants, and bacteria. Fish and plants require oxygen to stay alive, and bacteria require oxygen to reproduce efficiently and complete their role in giving your plants the nitrate they use.
pH is referred to as the “master variable” as it determines many other water quality variables. Most importantly, a pH of 7.5 or higher is ideal for the nitrification process, and a pH of less than 6 does not allow for nitrification. pH also affects the nutrient solubility of water. Optimal pH levels for nutrient solubility is 6.5 or lower, so it is important to find a balance between allowing for nutrient solubility and nitrification. In aquaponics, we want to aim between 6.5 and 7 with about 6.8 being optimal. This allows our fish plants and microbes all to benefit from the aquaponics environment.
Finally, you need to know the source and the contents of your water. If you are on city water, your water will likely have contaminants such as chlorine and fluoride which are harmful to our ecosystem. Know your water source and if you need to filter your water to set yourself up for success.
The first step toward an effective filtration process is the removal of solid waste. Roughly a quarter of fish feed is converted to solid waste, which will enter the hydroponic component of your system and steal oxygen from your plants as it decays if not removed. To prevent this from happening, remove solids from your flow stream through filtering or settling. A cone bottom barrel designed so the water flows radially will cause solids to settle. Remove them as necessary to keep your system humming and your harvests top notch!
The next step is biofiltration, which is the removal of ammonia from water through nitrifying bacteria. If your system itself lacks the surface area to support an adequate population of bacteria, you may need to purchase or build a biofilter to attach to your system.
3) Feed your Fish
The most effective aquaponic systems maintain a constant feeding rate. To accomplish this, you have a choice of two methods. The first involves separate tanks for fish at different growth levels. When the last group is harvested, your system will experience a 25-30% drop in feeding rate that gradually increases over the next cycle. So this option is tough for hobbyists and smaller systems as nutrient drop low between stockings and will affect the quality of the harvest. Large-scale commercial growers use this option because they have many cohorts of fish and large volumes of fish to minimize the impact of a single harvest.
You can also keep all sized fish in the same tank, periodically harvesting the largest fish and replenishing the system with fingerlings. This results in slight fluctuations in feeding rates throughout the cycle. This system requires less space but does cause minor mortality among fish. However, this is usually the simplest option for hobbyists and small-scale growers.
Feed input will play a role in determining the amount of plants and fish you can grow based on your desired output. The feeding rate ratio is the amount of fish feed input daily per square meter of plant growing area.
4) Avoid Biofouling
Use of aggregates as growing media can trap solid waste. As we know, solid waste reduces oxygen levels as it decays, harming plant growth. The same problem can arise with too small pipes, which can trap solid waste as it builds up. Spaghetti tubes to deliver water to individual plants can even clog completely, stopping all water flow. Large pipes located downstream and low water temperatures can prevent biofouling.
5) Avoid Pesticides and Chemical Treatments
An aquaponic system is a completely functioning ecosystem that maintains itself through natural cycles. Additives such as pesticides, fungicides and chemical treatments, which are used to increase productivity in conventional agriculture, can be harmful to aquaponic systems. Pesticides used to prevent weeds and insects from harming your plants can kill your fish if added to your aquaponic system. Likewise, chemical treatments intended to treat parasites and diseases in fish can harm your plants. That’s why we grow sturdier fish species like koi and make use of best management practices.
If intensive pest management becomes necessary, your best option is biological control methods. Biological controls are pest control mechanisms that use other living organisms to naturally control parasites, insects, disease and weeds. These organisms are typically predators that feed on pests. Biological controls require a greater deal of management, however, fortunately, have been the subject of a great deal of study lately and new methods are rapidly becoming available. Ladybugs and praying manti are the two beneficial insects we utilize to maintain pest free systems and top quality produce.
6) Plan Your System
Before you begin, make sure you have a thorough and well thought out design for your system. To get started, follow three simple steps to develop your plan.
We’ve dedicated a whole section of our website to help others learn proper system design. Start with our start-here guide if you’re brand new. This interactive pdf will walk you through the process of starting your first system from concept phase.
For more advanced help visit for advanced help on specific topics check out help.trifectaecosystems.com or chat with us in the chat box on the bottom right of this page!.
7) Connect with the Community
The best tip to succeed in aquaponics is to reach out to other growers. There are tons of online resources to help you learn and grow, from classes to blogs to video tutorials. Take advantage of the services we offer at Trifecta Ecosystems, join our community, share ideas and best practices and learn from the wonderful aquaponics community. There are dozens of Facebook groups out there and the industry professionals are on the majority of them. Get your questions answered by those who’ve been successful for years!
Following these 7 keys to the perfect harvest will have you well on your way to growing like a professional and ensure you are getting the most out of your aquaponics system.