Backyard Aquaponics
A place to discuss aquaponics

This is my most recent build. It's my Quarentine system...and it's still a work in progress.
I have two of these tubs. One isn't usable right now.

I ended up getting an amazing deal on the 2 inch foam that I insulated the tank with through craigslist. this is actually excess from another project. It is further buried about 17 inches in the ground. Right now it has a 4x8 foot bed, about a foot deep.

The media is a mix of about 50% expanded clay, 40% perlite, and 10% scoria or black lava rock.

I'd like to eventually add the other tank, with another bed above it, only less buried, so it could be constant height, with this one as a fluctuating sump.

The pump is running continuously, and it is currently flood and drain with a bell siphon.

Great sump tank. Is the top growbed ply with liner?

Hey Asitis,
I love these tanks. I have another one just like it, but I'm trying to sort out a few things with it. I'd like this finished one to be the sump, and If I can get my hands on a taller tank, I'd Like to go CHOP. I have an idea (probably already done) to do a modified CHOP system with two of the blue tanks.

The idea is to have this one in the ground, the other about a foot higher, so it keeps constant height, flows into some kind of filtration box, then into the sump, where water would be pumped to the grow beds. Thinking of keeping the GB over the CH fish tank at constant flood, so the tank would be constantly having movement and increased aeration.
Once cycled, I'm thinking of using the current tank as a FT for now.

The growbed is two stacked layers of 2x8, and 2x6 timbers. The bottom is 3/4" plywood.

The liner is Duraskrim reinforced liner made here in California. It is pretty durable stuff, and the it has reinforcement, so if it gets a hole, it can't spread. I actually took a very sharp craggy piece of scoria/lava, and tried very hard to puncture the liner. It wasn't easy. So, I am definitely satisfied with it.

It is pricey, but I have bought nearly everything for my systems secondhand, or picked it up for free. I got an almost full roll for a ridiculously good price on Craigslist, which I'm not sure if you have out there, but I think the equivalent is Gumtree.

The only major things that I have had to buy new at full price were some of the pipes, the perlite gravel, and my pumps.

Has anybody here welded poly pond liner?
I have been trying, but i keep getting leaks. I'm trying to make a fitted liner for an old leaky circular wooden hot tub.I want to use this as my fishtank, since it holds about 475 gallons, and is a good height.

And, it's just sitting around. I had a roll of poly liner that I've used for my growbeds, the issue was that it was only six feet in width, and I needed it to be around 13 feet in width if I was to just fold it into the round shape.

So, I cut a five foot round circle, and cut a length that would make the radius and went at it with a plastic welder and a roller for pressure.I made some cuts that would allow it to fold around the sides. I proceeded to heat and roll when the plastic got shiny and sticky. I did this both on the outside and inside of the shell that I created.

The liner has a scrim reinforcement, and I kept having issues with it getting too hot, and the reinforcement popping through the hot poly, making an open hole. Most of these are tiny, less than a quarter inch. But, maybe the reinforcement is what is making the welding tricky as well, it creates a slightly raised grid in the plastic

I am almost ready to give up and buy an EPDM liner. I found someone selling some lightly used liner for 50 cents a square foot, but then i will have folds.

Some background factors to consider:
I have more time than money right now.
Part of the allure to aquaponics for me is being able to raise fish without an outlandish price tag.
The other part is the veggies of course.
I tend to give myself ridiculous challenges.
I like to recycle things.
I'd prefer to stick wit the poly because of it's inert nature.

Option 1: keep trying to weld. Maybe I'm using too cool a setting on the welder for fear of the reinforcement popping through. I haven't found any examples of anybody welding this type of liner to follow. It's duraskrim liner. Cost: about 30 bucks. Time already invested, about 12 hours.

Option 2: Check a thick vinyl liner that i also have laying around for leakage, put that in, maybe just use that, or put the poly inside the vinyl liner, so it catches any leaked water. Cost, about 30 bucks. Vinyl liner was a freebie.

Option 3: Buy an epdm liner: Cost ~120 bucks.

Option 4: Buy a poly tank, and stop being stupid......Priceless.
( I found the one that I think I want, but it's far from my house, and I don't have a truck...)

Option 5: I have some elastomeric paint (like 40 gallons), that supposedly stretches 700% or something like that. It says that it can be used for an underlayment for liquid rubber for water holding purposes. Maybe this could seal the cracks, then the liner could go over it, or I could try liquid rubber. Unsure of cost of the liquid rubber and the quantity needed.

Option 6: Try filling the small openings with silicone. And, hope biofilm will do the rest. (I was able to get my fingernail in between the liner that I thought was welded in some spots, and to pull it apart a bit. )

Any ribbing, ridicule, thoughts, ideas, tips, or encouragement is appreciated....

On the bright side, this system is almost cycled!!

Ammonia is being converted in less than a day.... Put up shade cloth today, our temps jumped into the 90's, and the baby plants were getting sunburn. I'm testing out dwarf tomato plants this time around, supposed to only get about a foot and a half tall. We'll see.

I decided to, um, be brave, and turn up the heat a little, and well,, some parts fused beautifully. Some, well, just didn't, and got worse....Lesson #1, don't weld plastic in the dark.....

Will that RTT Sealant that I painted my pond with is really tacky. I got an old 1000L IBC from the local tip. It had some damage because it had been used as rubbish bin for mechanical parts. It had at least one small hole and another couple of spots that may have leaked. I gave it a good clean out using a citrus cleaner, a scouring pad and a pressure cleaner. It came up white again. I then gave it a splash of the blue RTT Sealant over each patch of damage and achieved a perfect seal. I think it should work on anything where you can clean the surface really well and preferably scuff it lightly. The coating is highly flexible.

We don't seem to have a lot of potable/ food grade products like that here in the US. I don't know why exactly. I've found a blue rubber type coating that says it can be used on potable tanks/ cisterns, but then people have had it turn their water blue and give it a chemical taste over time. I was thinking epoxy might be a solution, but not sure of how to estimate the coverage/ quantity needed. One gallon, three gallons??
I keep getting closer to the EPDM liner.....

I used to do a bit of steel boat building. We used Dimet products but I think they are now Jotun marine coatings. It might be worth taking a look at their water tank coatings. These are food safe and should be suitable for the fish. We used Epoxy Tar in the 70's but I think they were outlawed and replaced by food safe polymers.

I won't lie..... I use Flex seal tape to patch 2 inch miss cut holes in my IBC and sump from years ago.... Yeah works like it does in TV and even stuck to the wet surface. I put a peice on both sides of the hole. Now I can fill my FT and sump all the way up.

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So this is the system that I'm adding almost 2 foot deep beds to. It's going to become chop system after all. I currently have 20 advanced channel catfish fingerlings in the sump to run the system for now.

I am going to try using a piece of pond liner, folded into the wooden tub for the fish tank. I was able to pick up a big piece of heavy duty poly pond liner from a big aquaponics operation that is relocating soon for 40 bucks, I think it is about 15x15 feet, and 40 mil.

Hi Will,
I have used poly ethylene Grunt Builders Plastic in a grow bed, its quite thin so needs support but works well and is very cheap. Keep the exposed edges out of the sun and it will last a long time.

I planted the only strawberries that I could find in a local nursery. Turns out they have a really pretty flower, but a small fruit. They taste ok. I want to salt this system since I have catfish in it, and a few of them have bumped their faces on the support system that was built into the tank. Any experiences with salting systems with strawberries? I was thinking of going up to around 1ppt. Maybe i should go higher, since they just taste ok...

I'm working on expanding, and just finished a 4x8 media bed that is two feet deep. The bed is split down the middle, so I can run half constant flow, and half on a siphon.

The current fish tank will become the sump.

Things didn't work out with the welding of the liner. I kept having a few slow leaks.
Luckily, I found a few fiberglass tanks, really close by, and at a good price. One is 480 gallons, and the other is 400.

I really want to put a window into the bigger one, but have zero experience with fiberglass. And, I need to get a move on the rest of the build.

These are the tanks, they were used for water, but I'm going to coat the inside with a non toxic fish safe epoxy.