Plumbing & Thermodynamics
Hi folks – back again with another edition of “Aquaponics: The Definitive Reference”. No doubt you are chomping at the bit for more information, so let’s get straight to it.
Plumbing
Plumbing in aquaponics can be broken down into two basic categories – the pipe and the fittings. Properly designing your system well in advance (on paper or in a computer) will allow for accurate estimations of the amount of plumbing materials you will need to purchase. As has been mentioned in edition #2, steer well clear of green garden hoses. This type of hose is not suitable for aquaponics and in no way should it be considered 'safe'.
Pictured are 3 types of pipe/hose considered suitable for permanent use in recirculating aquaponics systems:
- Black HDPE pipe (blue or green stripe):
- White rigid PVC-U pipe:
- Black reinforced flexible PVC hose:
All of these pipes and hoses are considered safe (and legal) for commercial aquaponic and food transport applications in Australia, as per the Australia/New Zealand Food Standards Code (Standard 1.4.1, and Standard 1.4.3).
While this specific information only applies directly to Australia/NZ, it does provide a prompt for people from other nations to seek out the relevant guidelines and authorities in their area. At the very least, using the products and materials suggested here will guarantee your personal health. Furthermore, it is very likely that these products will be considered legally suitable for commercial aquaponics systems in your country also.
'Standards Australia' has developed an Australian standard for plastic materials for food contact use, known as Australian Standard AS 2070 –1999. AS 2070 specifies a number of requirements that pipes and fittings will normally not meet because the standard addresses the manufacture and packaging of foods, rather than transport in piping systems (although that is not specifically stated).
Therefore, according to a document entitled “PVC and Polyethylene Pipe Systems for Food Transport Applications”, published by the Plastics Industry Pipe Association of Australia Limited in 2011:
“Product standards for PVC and Polyethylene pipes and fittings do not require conformance to AS 2070-1999 requirements, because a major application for these pipe systems is the transport of potable water at 20º C and the performance requirements address this application.”
Specifics of the Australia New Zealand Food Standards Code – Standard 1.4.1 – 'Contaminants and Natural Toxicants' can be found at http://www.comlaw.gov.au/
Specifics of the Australia New Zealand Food Standards Code – Standard 1.4.3 – 'Articles and Materials in Contact with Food' can be found at http://www.comlaw.gov.au/
My personal preference in pipe/hose types is most certainly #3, the black reinforced flexible PVC hose. While most flexible PVC products are not suitable for food or water, purpose-built products such as food-safe vinyl tubing are available. The main advantage in an aquaponics setting is the smooth interior bore, combined with the lack of a requirement to install elbow-joiners for bends. This makes for very low internal back-pressure, allowing us to use the absolute minimum electrical energy required to achieve our desired water flow rate. This efficiency of water movement is true for both the delivery and return of water from the beds. Water returning rapidly to the tank under gravity imparts kinetic energy to the fish tank reservoir, which results in turbulence and improved aeration. This hose is non-kink, UV stabilised, abrasion resistant and suitable for fresh water or marine applications. Frankly it is as tough as nails and is not overly expensive.
Fittings
Plumbing fittings in aquaponics can be broken down into three basic categories – tank outlets, valves and joiners. When using the blue or green stripe black HDPE pipe or the rigid PVC, you are quite limited to what fittings you can use. There are particular fittings for both of these pipe types and not much else will sufficiently do the job. In this case, any plumbing supplies or hardware store should be able to help you out. Just be prepared for a shock when the total price arrives.
Flexible PVC hose can quite happily accept the similarly sized 'threaded' or 'barbed', push or screw-in joiners, valves and outlets. This is a great bonus because the fittings are cheap and many different fitting types can still give a water-tight seal with this type of hose.
For each grow-bed you will need two Nyglass (glass reinforced nylon) barbed tank outlets like this:
For each grow-bed, you will also need a single barbed inline poly valve, such as the 'Green Back' poly valves offered by Antelco:
Plumbing Sizes
This is very simple, as I have devised a straight-forward rule for plumbing sizes that applies to a very wide range of bed sizes:
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