Backyard Aquaponics
A place to discuss aquaponics

Yeah I've got a list of people to talk today about which way to go. I've also though about ditching the liner idea and going for an onion tank instead.

Have you considered getting a bit of thin sheet metal (eg Bluescope steel Aquaplate) cut for the base, then crimping it around and onto the corrugated walls?

Then just generously silicone both the inside join and outside to make it waterproof and neat looking.

This is was how our corrugated iron tank supplier was making our big 5000 litre round tanks. This worked out cheaper and easier than bulk roll purchased pond liner @ trade prices:

(ignore the stainless steel frame - that was used to support a hinged hardwood decking cover over the top)

Thanks for the suggestion Jono but I'm not that confident in my metal work skills

my friend don't doubt the power of silicone.. that's what makes the main seal Many a glass aquarium tank is held together by silicone alone

Apply heaps of the stuff, then just smooth it over with the end of the tube it came in. Then it doesn't really matter too much about the quality of the steel crimping job underneath, and it will hide all the rivets & screws used too

Might still be worth getting a quote at least from a local water tank supplier? I can't remember what our bloke charged to put the base on that tank above but it wasn't much extra

How do those onion tanks compare to liner pricewise?

Oh I know and love silicon but my metal work skill not so good. Plus the bottom is a bit roughly cut. I guess I could bodge something, slicon to a fare thee well and then paint with bitumen.

Look I'll add it to the list for consideration.

Don't know about the onion tanks yet no one has got back to me.

What is the cost of the liner? What is your time worth? What is the volume of water it would hold?

Different liners different costs.

Elcheapo is not much Geoff miller do a fitted liner for $250 but it is not exactly transportable. If I was going to be here for a while I'd go with one of their liners but if I have to move in one or two years it wouldn't be worth it.

More expensive would be EDPM at about $15/m which would survive use and reuse quite well.

Each tank would hold about 10kL and my time is not worth much at the moment.

How sturdy are the onion tanks? I did a google on them, looks like if you leant against it, bumped into it on the wrong spot, or had a crazy labrador body slam it (a big possibility in my house).

Are you going to start a thread on the new DWC setup?

They are meant for portable water storage in emergency situations so they I imagine that they are not that fragile

This is not really a suggestion for how to do this but more a thought. If this were sitting on concrete, I wonder if you could join extruded polystyrene sheets using epoxy to make a base slightly larger than the tank. Then route a circular groove the size of the tank for it to sit in. Last cut out a circular piece of EPDM or suitable pond liner to fit the bottom and run a bead of epoxy to seal it to the tank.

I suppose you might even be able to skip the foam and just use epoxy to seal the joint between the liner and tank if it's on concrete but I think having the groove would help prevent problems and you could use the groove to cut your liner.

Come to think of it you could just use the foam without the liner. Just seal the grove in the bottom where the tank sits on the foam. Depends on the foam of course but would be pretty slick. Wouldn't add much weight to the tank.

The idea comes loosely from boatbuilding and their use of epoxy for stitch and glue style building.

In the long run you're going to want a heat molded liner made for your size round tank. It's one thing if you're only going to use it for water storage forever. It's completely different if you're going to use them for possible fish culture tanks down the road.

I'm on my phone and can't remember the original dims of the liner but if it's wide enough, you can cut the round bottom piece slightly larger, then cut your tank wall as a single piece. Use double sided Epdm bonding tape (use the wide 6" stuff) and lay the top of the circle over the side wall bottom. When you are done with the job, hit the seem all the way around with an air compressor nozzle to make sure there aren't any gaps. A bit tedious but can be done. if you go to Firestone's website, they have a video tutorial that will walk you through the entire seeming process. I hope this helps!

Its all useful even the bits that are not useful, if you understand me.

I've watched the EDPM fabricating videos before but I don't remember seeing anything on how to form a curved edge.

How do you get the 6" tape to form to the curve without rippling and creating points where it will leak?

I like this idea, though I'm not sure if Epoxy will bond to EPDM? Then you will need to find a fish safe epoxy or bonding agent too, as I have killed fish in the past by using an epoxy I thought would be safe (it had potable water certificates) but wasn't

Chemical resistance is often a selling point for pondliners, but it can make them a pain to join without the right stuff

Don't know how well epdm would fold... I used plain Greenhouse film for my first tank. Held up longer than the greenhouse did (R.I.P. blizzard of 2013)...

Hi Poppa,

I'd say welcome to the forum but you have been around for a while

Have you posted those pics previously to the forum?

I've seen them before

I think it was when I was looking for info on how to engineer that style of wire frame tank.

Yes what you have posted would work and if I go the elcheapo route then that is what i think I will do. Similar at least anyway.