Backyard Aquaponics
A place to discuss aquaponics

Hey Iv been ringing around today looking for Aquatic Safe Plastic for liners.

Most of the places i have called say they dont understand what i mean by aquatic safe and you try to explain and they have no idea and get frustrated.

I just want to know if anyone can tell me if "Generic Black Plastic" is safe... i cant see why it wouldnt be if people are using Pools etc.

i know the stuff they use under concrete for example is available cheaply, its robust, and u can get it in 3600, 4800, 5400 Widths by any lenght u want (upto 100mts i guess now theres a Huge tank!!!!)

there is also a white hothouse type plastic available, fair priced and large widths and obviously a clear hothouse plastic.

its hard to go into details with some ppl out there about what kind of plastic it is or whats in it etc.... anyone that can advise or knows what i can look for as for plastic content and whats bad for our finned friends....

kids r biting.... gotta run

Talk "pond liners"... and they'll know what your talking about... EPDM is best...

Don't use builders "black" plastic...

Man That stuff is Pricy!!!

By the time i line my tank, sump & Bed it's be cheaper to buy 3 IBC's hahaha

i found this Pool Liner Stuff


Made from heavy duty Nylex 0.5mm PVC Vinyl of the most durable materials to
maximize the life of your pool
Fade resident
Stain resident
Easy clean
UV stablised

Product Features
Size : 0.5mm thick x 2.250mm wide
Pile Material Deep Blue colour: PVC Vinyl

im sure its not as good as the other stuff, but as long as its safe for fish.... which i guess PVC is it should do the trick in my tank's as they are going to be Fully Seal welded.

@ 9.95 Per Lineal mt x 2250 wide... its affordable.

The problem with some pool liner PVC vinyl is that it has been treated with additives to keep it from growing algae, mold, and bacteria. These chemicals can be bad for fish and definitely bad for the bio-filter bacteria. The people selling the stuff are not really going to know much about that since they are marketing it for use in swimming pools and therefore are not interested in being food safe of fish safe and the chemical additives are actually a selling point for use in swimming pools though not for us.

Anyway, at some point you will have to assess your own risks and decide for yourself what is appropriate.

However, I know of people who have struggled with unexplained fish deaths when using cheap swimming pools for their fish tanks. Now proof what was causing the illnesses and they kept treating as if it was a bacterial infection but I fear it could also have been skin sensitivity to the chemicals from the pools leaving the catfish open to skin infections and therefor the infection was actually a symptom of a larger problem.

So, the question is, if you go with a cheaper alternative, what are you going to do if the liner doesn't stand up to the punishment of growbed media and digging or even worse, you start having unexplained fish deaths (and they likely won't start right away so there will be some investment into the fish if the liners are the problem.)

I've also done constructed lumber grow beds even with the really high quality liner, I'm now changing over to stock tanks for grow beds since termites won't realize when they have left the wood and entered the liner until it is probably too late and now they are getting intermittently wet (or perhaps they like that.) If you do go with liner, make sure you think about things like termites.

I've even known of people using builders plastic but that means probably having to remove the gravel and replace the liner on a regular basis. I've seen a root penetrate through such plastic and cause leaking to start. I didn't expect mustard roots to be so tough.

Good Luck!

I used 5 layers of builders plastic in my home system for the fish tank, but there is no way known that I would use it for growbeds!

It has been proven several times that pool grade PVC is toxic, and results in mass fish death after around 6 months. Same thing with unlined galvanized tanks.


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I would definitely recommend the EPDM liner
I found this site to be a good source especially with their freight deal
http://www.rockaroundtheblock.com.au/de ... sp?c=11815

Thanks Heaps Guys, i really need to do it right the first time, i guess you guys see this a lot a Noob comes in with ideas and trys to reinvent the wheel, then fails hahaha

after pricing the Steel for my tanks (Even at Cost on work accounts) , with liners, and insuation, stands, and all the other gear i need its worked out to be well over what i expected it to be... righhht over

i figure even the $160 for an IBC is Very Good Price, pity i cant book them up on a work account anywhere (iv been trying)

i could prob buy 3-4 IBC's for the same price i was going to spend, so i reckon i will just buy one in the next week or two that will give me my Sump and a grow bed, at least i can start cycling with that and then grab another IBC as my tank when i can spare the funds and slowly build onto that, (another IBC gives me 2 more beds) can still insulate an IBC i guess and it will save me a lot of work on building steel tanks, Lining them, ETC plus they come with Free Stands heh

Im So Glad there is a forum so i can learn !!!

thanks heaps guys!

I've been coming to the conclusion that liner is only appropriate under certain circumstances.

1-Digging in ground pond
2-Long on the ground DWC raceways or beds (so long as no wood is involved.)
3-you have a free tank that needs to be lined to be fish safe
4-cheap tank made with fence panels that needs liner.
5-you space/size requirements are so tight that you need to build custom beds and tanks and you know the dangers of liner and whatever materials you are working with.

I do like using liner but I know now that it really isn't appropriate for all things. I think you will be glad you are not trying to plumb through metal and liner, just seems that would be a pain. Lumber and liner was bad enough.

And the IBC's or if you can get reasonable prices on stock tanks they can be great to work with plus the ability to add to the system incrementally. Just put a little extra thought into placement of the first ones so you won't have to move them as you expand and the same extra through to the plumbing so adding on will be easier. Make drains extra big to handle the flow of additional beds later etc.

Good Luck

TClynx posted a decent image of a "metal" tank using liner. Seen same method used with growbeds and some 10000l tanks.

The fence panel and liner I think works well enough for tanks (though I'm not all that happy with the folds but to get a fitted liner would cost quite a bit more and then there is the added danger of leaks along the seam.)

If I were to make round grow beds this way (and I don't think I would really recommend it.) I would definitely go with the heavier fence panels with smaller squares as the gravel has an advantage when it comes to pushing out, the gravel if it gets pressed out won't press back in and will cause more bulging between wires and put more stress on the liner. Also, I have seen issues with plumbing trough liner below the soil line, a tank like this is not going to be easy to lift up on any sort of support and the plumbing out the bottom of such would be in the dirt to drain back to a sump. Bulkhead fittings down in the dirt have shown me that tree roots can be pretty tricky. Keep this in mind if you dig any in ground tanks and decided to plumb through them rather than simply sending the pipes up and over the side. My old hole in the ground sump tank had been loosing water. When I dismantled it, I found tree roots had invaded the bulkhead fittings below the soil line. The uniseals where I forced them in and then cut an x in the liner to push the pipe through were intact but those usually cause pulled muscles to install in such a situation and then trying to glue pipe down in the dirt is really nasty too.

Liner is best used where you can leave it intact and avoid plumbing through it. Where you must plumb through it, make sure you can see both sides of the fitting for inspection and removal of invading trees or simply to keep an eye out for leaks.

When plumbing through liner you must have a backing for support and make sure the liner isn't going to try to stretch away from the fitting as this will cause tearing and leaking.

For my big fence panel tank, I used a 3" uniseal to plumb through it. It was nearly impossible to do (Myself and the cook working on it and he is a brute, if he had trouble I don't expect a normal person to manage without injury.)

Tank fitting would probably be easier than uniseal for that. Wide flange and you just screw it tight.

Yep probably would but I was saving money. If I were to do it again, I would go for a large bulkhead fitting or tank fitting of some sort and save the pain and suffering.

I still use lots of uniseals but mainly only through tanks ans stuff. They are perfect for the rounded tanks or buckets where a bulkead fitting won't work.

I went Scouting today for IBC's and stock troughs,

Some prices on Poly Stock troughs for tho's who may want to know

250l $169
500L $260
1000L $485

there just the basic round trough with no float or holes etc
My Steel 1200l tank was going to cost round $500 to make (inc liner, stand, Lid), and about 4/5h labour, much rather work those hours n buy a stock tank on the way home

Missed out on a Older IBC for $70 today.... but still hunting $160 is the lowest price iv found.

i scored some Washing machine pumps today, the look near new and there inline ones, not sure if anyone has used these before i'm sure they would be ok to move water around not just sure how economical at .85a but they were free and they work (Brother is a sparky and he threw some 3-Pin Plugs on them for me)

Your brother might already have mentioned this but the washing machine pumps are probably not rated for continuous operation.

notes about pumps, you want ones that are safe for fish. This means a pump that has no metals to corrode touching the water. Stainless steel is about the only fish safe metal for this purpose. And you also want to make sure it is a pump that can't possibly leak any sort of lubrication into the water. Most pumps not meant for fish systems have seals and lubrication that occasionally need replacing. If it might occasionally needs replacing, it could fail and leak oil into the water which could quickly kill all fish by coating their gills and blocking their ability to get oxygen.

For some of these same reasons, regular air compressors like for tools and such, are also generally not appropriate for fish systems. That is besides the fact that a regular air compressor is really noisy and would use lots of electricity to run air for an AP system. They are generally overkill on the pressure and low on volume.