Mineralization in aquaponics
Have you ever tried to grow fruiting crops in aquaponics? If so, you will know that it’s difficult because the way most aquaponic systems are designed it is easier to grow leafy green. The reason for this is because you normally dump out a lot of the micro nutrients when you clean filters as the nitrate levels raise so much faster than the other nutrients. This is because nitrification happens faster than the process of mineralization. The mineralization process takes place naturally in the grow bed but the isolation in a offline tank Increases the nutrient profile of the system by less dumping of solid waste and offers an opportunity into nutrient manipulation/control.
So what should you do?
Many people have found success by supplementing the fish waste with seaweed extracts and other nutrients. But what you should know before you introduce an extra fertilizer at an extra cost and becoming even more dependent on another product to grow your food is that you get more complete mineralization and certainly more rapid mineralization.
This post will tell you what you need to know to make your current amount of fish feed be able to support a larger amount of fruiting plant crops than it currently does.
What is mineralization?
Mineralizing is not to be confused with nitrification. Nitrification is the process of oxidation in which fish waste is converted to plant food. (Ammonia to nitrite to nitrate) This process is for nitrogen whereas mineralization is where all the other minerals are generated from fish waste by heterotrophic bacteria breaking down organic matter into all the other nutrients (P,K,Ca,Mg,S, Fe, and the micronutrients)
What is the benefit of a mineralization tank in aquaponics?
If you are looking for a way to grow more nutrient dense foods like pumpkins squash corn etc, the best method to ensure you end up with a process that lets you concentrate your fish solids and process them to release the locked up nutrients is by looking at these things.
Solid removal is an important addition to aquaponic systems it helps prolong the cleaning of media filled grow beds and it reduces the waste that will clink to plant roots in DWC that increases the need for dissolved oxygen. Problems with media beds accumulating too much solids usually means the media is too fine or the fish stocking density is too high and your producing more waste than your system can handle. To be more efficient we can add a mechanical filter and capture the solid waste before the grow beds. The fish by-products come mainly from two sources, the kidneys and the digestive system: Waste from the kidneys is mainly ammonia which is released through their gills and the urinary pore. Waste from the digestive system is composed by a range of organic compounds. These organic compounds are in forms that plants can’t use readily mineralization is the process that makes these compounds water soluble and plant available
A mineralization tank can reduce pest attacks
Nitrates with does degas from the system due anaerobic conditions is actually a good thing… nitrate itself is the real reason why most of our systems are working how it should and also why we are hit with so much pests. Because they are attracted to the high nitrates assimilation in the leaves and cellular elongation that nitrates causes with plants can increases pores sizes and makes it easier for pests to attack the plants
How the mineralization process works?
It is a rapid composting of the fish solid waste. In fact solids will completely mineralize in about 4 weeks in aerobic digestion. Mineralization is the biological break down of the solid fish waste. The difference between aerobic and anaerobic is that the nitrogen gets gassed off in anaerobic digestion
How to connect the mineralization tank to the system?
For optimal results the best place is to connect onto the mechanical filtration tank. Make sure your filters lets you backwash the fish solids automatically. If it does not, you will have trouble as you will have to collect the solids manually when cleaning the filter and this will take up lots of valuable time. Some people filter the water before transferring and some will let the water settle and decant the clear water off the top.
Off line systems are best because they allow you to turn off the aeration and water movement to let the sludge settle so you can decant the clear nutrient rich water from the top, regardless of how long the tank was anaerobic you only have to re-aerate for 24 hours to be sure it is safe and then it is good to put back into your system.
Good mineralization tank design?
MT’s are just tanks filled with water, fish solids, and uneaten feed complemented with a high concentration of dissolved oxygen to macerate the solids and break them down into usable nutrients. With any digester you want to maximize the hydraulic retention time (HRT), but the solids retention time (SRT) is a more critical component, however, on a small scale, fully mixed reactor like these they can be assumed synonymous. Ideally one wants to concentrate the wastes and minimize flow to achieve longer HRTs. The best feature is that you never have to fully clean out the mineralization tank We have found that air lift vortex brewers are excellent for the mineralization tanks and can be used for brewing compost tea as well it is best used as a batch processor. The best low-tech indication is smell, IMO. Even fully anaerobic digested waste should not have unpleasant odors.
Wicking bed is an excellent addition to any aquaponic system
Ensure your aquaponic system has a wicking bed so you can dump your thickest sludge into it. Any good mineralizer should let you easily drain completely empty. While not necessary, some other great bonus features of a great offline mineralization are automatically fill up from your filters , automatically decant into your grow beds and automatically dump the sludge to the wicking beds, and a good automatic pH reader to tell you when your pH has change as an indicator of changes in the composition.
Now that you know how to add this process into your system, you’re ready to grow more nutrient dense food without worrying about depending upon extra bottles of fertilizer.