Richard bray

Biological Filter
A biological filter does not catch or filter out visible waste. Its purpose is to filter out ammonia waste (urine) and convert it into nitrogen for plants; a process called nitrification, and to break down solid waste to convert it to other vitamins and nutrients; a process called mineralization.
Any surface area within a system can support the bacteria necessary for these processes, which is why biological filters are just a collection of small particles that increase the amount of available surface area.
These particles can be plastic balls, clay pebbles, rocks, plastic beads, or a number of other inert, small, or porous materials. In media-filled grow beds, the media acts as a biological filter. In all other systems, you must add a biological filter by plumbing in a tank full of media that allows the water to flow through on its way to the grow beds.
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Solids Filter
A solids filter is meant to catch and filter out solid fish waste, excess feed, and dead plant material. Solids can be trapped in a biological filter, but the purpose of a solids filter is to remove visible waste.
Bacteria generally cannot keep up with the amount of waste that fish produce, and it would clog pipes and become toxic for fish if it kept recirculating through the system. A solids filter will help remove solids in a tank where they can settle and be easily removed from the system if there is too much buildup.
Water
Water is an obvious necessary component in an aquaponic system. Before you build your system, test your water. There are many additives in tap water, like chlorine, that can cause serious harm to your fish.
You should also test your water’s pH, nutrient, mineral content, and salt content. A good rule of thumb is that if you won’t drink your tap water, it's not suitable for aquaponics.
It’s important to understand the properties of your water before you design your system, because it will influence your maintenance responsibilities. Part of regular maintenance on an aquaponic system.
is draining off a few gallons of water and replacing it with fresh water
If your system runs at a pH of 7.2, but your tap water is 6.3, you need to adjust the pH so you don’t shock your system. If your tap water has chlorine, you need to let it sit for at least 24 hours so the chlorine will dissipate. Many elements that are harmless for humans are
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detrimental to fish, so do an in-depth test on your source water before you build anything.