Backyard Aquaponics
A place to discuss aquaponics

What are everyone's thoughts about materials to line fully supported fish ponds and grow beds. I have heard of EPDM and PVC. Are any of these better than others? Are there any pitfalls or things to watch out for such as certain material to avoid. Also, what are good thickness? Are there any good articles or resources that you could link too?

Any assistance is appreciated.

I would avoid liners using PVC due to the plasticizers added to allow the material to be flexible. I would recommend using polyethylene materials since they are food grade and less likely to cause health problems in a recirc system. In my opinion, the survey is still out on if EPDM is bad - I have seen articles that say it's bad and some that say it's fine. In terms of thickness, 20 mil or higher is best - the higher you go the more difficult it is to shape. Duraskrim 20WW or something similar is a good choice.

It think that the use and selection of a liner must also be compared to the size and materials used to construct the supporting structure.
Grow beds for instance usually have coarse media which is not only rough but heavy and can puncture liners. The materials that support the liner can have an effect on it's performance by becoming a squeeze point(s) and or allowing the liner to stretch too much.
Good lining material is expensive and not puncture proof, so when considering how much work and cost is involved to build the supporting structure and remove and repair (if you can) a liner it makes mono liners such as IBC PE and stainless look more attractive.

Pete.

How is stainless affordable? And what is PE?

Polyethylene = PE

Rather than a soft liner you can fibreglass the interior of the growbed

In my opinion , having built both a stainless and an IBC system of similar sizes and having gone through the designs of other materials I think stainless for GB's are the ducks nuts.

Sure the stainless steel sheet is size for size more expensive than most other materials, however because of it's inherent strength and corrosion resistance a lesser thickness is required because material reserves are not needed.
Because of it's strength it can be folded, drilled and welded or riveted into a self supporting shape capable of supporting more than the weight of gravel and water that it could hold in volume. With the use of some PVC fittings and some handyman skills a visit to your local sheet metal shop standard sheets could be converted into grow beds that will out live their makers and their children.
Although I got 9 IBC's really cheap I found for the similar size unit the stainless GB's were less messing around, easier to insulate and faster to build. Due to the short life expectancy of the polyethylene liners I am not looking forward to reworking them, and to prolong their life will try to hide them from the sun.
I found good quality liners were not puncture proof either so that meant that cheaper steels or timbers used for support couldn't be used due to them being able to rot.

Pete.

I have reconsidered my design as I have found a local source for used 55 gallon drums for $12 a piece.

I have no welding capability so that would make it hard to work with SS. What do you recon your cost is for an IBC size grow bed. I can't help but being skeptical about the cost effectiveness of it. Further more I am a novice so maybe making the investment in a lifetime quality piece of a equipment for something I just got into 2 months ago might not be the right choice right now. Are there other people using SS?

PVC (and possibly EPDM) liners are bad? I'm using a PVC pond liner on one of my tanks because I figured "hey - this product was made to hold fish - it must be OK?".

My outdoor pond (not AP) is lined with EPDM and the fish seem happy enough.

Is the concern that EPDM and/or PVC leach into the veggies, or would it affect the fish directly?

Thanks.

When I started investigating what materials and types of systems newbees try to setup I found even with the evidence of thousands of operating systems world wide the newbees were still skeptical that either they could or the get system itself would work. This lead to most newbees starting out with the smallest cheapest systems that were so hard to maintain because of the low volumes, incorrect fittings and their desire to at least have a go.

In the short term AP is not a cheap way to obtain edible fish and veggies, there's lots of time and money to spend on a good long lasting system. So it makes sense to begin with some quality gear that can be expanded as you grow with it.
I used stainless for the reasons posted earlier and because I have the equipment to process it. Granted most people wont but that doesn't stop them from going to a sheet metal shop with a plan of sheet size, cutting, folding and welding instructions. That will save money because the sheety could easily quote it as he/she doesn't have to think about the design just do the work.

I used a down grade sheet (scratched and or dented) 10' x 5' 18 gauge (3000 x 1500 x 1.2 mm) 304 $172.00 to make a 2300 x 800 x 300 mm GB.

Pete.