Backyard Aquaponics
A place to discuss aquaponics

Not running AP out of a gal tank, but repaired a leaking 50,000L gal tank using Gripset 451 (from memory and avail at Bunnings) - water based and suitable for drinking water. Decided against the bitumen as I had to paint the stuff on inside the tank with minimal ventilation. Didn't want to take the roof off and just used the man hole. It cost <$400 in late 2007 all up and was like using very thick paint.

Do you run your AP on water out of the repaired tank? Just wondering whether we can confirm that it is safe for fish (what's deemed safe for drinking isn't always safe for everything else).

It said on the can suitable for human drinking (potable) water once cured, so I hope it's safe for fish! That said I'm still building my first AP system, so I ain't tested it on fish and only use the tank as a header tank for stock watering - but the can also said suitable for repairing leaking fish ponds. It's acrylic based I believe and once cured is impermeable and non toxic - mind you those with chemical sensitivities may disagree.

If it said it was suitable for fixing leaking fish ponds, then one would hope it's not toxic to fish...

Jimmy - feel your pain mate. I had Nickel leach out of my bathtubs which caused no end of troubles.

I also used Gripset 51 - http://www.gripset.com/handyman/product.php?productid=4
on my galv growbeds viewtopic.php?p=76289#p76289

That was 18 months ago, no associated problems that I am aware of.
Let it dry for a couple of weeks and then a good rinse.
Available from Bunnings or maybe try Bianco building supplies if you need allot.

Okay, so I finally got around to lining my growbeds (both were galvanised). I had some expensive pond liner lying around in the shed with no plans, so rather than buy some expensive bitumen I decided to make use of the pond liner.

I cut the liner into a circular base and 30cm strips, and then glued it all in place with aquarium-safe silicon (note: disposable gloves come in handy here!).



I needed to hold the sides in place while I was glueing, and had a brainwave that I could use fibreglass tent-poles - worked a treat!



The liner stayed in the sun for a week and then I was ready to test it for water-tightness (all good) and refill the growbed.



Now, according to the instructions on the silicon sealant, to be fish safe it needs a full rinse with water, drain, then refill with fresh water. I hope to get onto this in the next week, so soon we should have some new goldfish!

Way to go Jimmy...

In hindsight I could perhaps have removed the tarps and random chair from the background before taking the pictures...

nah

Looks good, Jimmy.

Any folks in the US have suggestions for lining products that are available here? I've had epoxy resin suggested. If I could find out what they use to seal the seams of galv water tanks I bet that would be great stuff, too: nice, flexible, tough. We have some great polyurethane caulks that could be spread nicely and are food safe, but are not intended as coatings and require 21days drying time before potable water contact..

I thought the chair was for you to sit on watching the plants grow.

Luv the idea of the fibreglass tent pole.

Malcolm

Not sure, but I've since discovered that the silicon aquarium sealant I used is not intended for permanently submerged conditions, unless beng used specifically on glass for aquariums (it says it can be used for other applications but not permanently submerged). Strange. So technically it was the wrong product to use. Still, no problems thus far; lots of healthy trout (which are particularly vulnerable to zinc) to prove it

I don't know how your hardware stores are organised over in the US, but I recently found the "right" products are not sold alongside the other adhesive / silicon sealants but rather are found in a whole other section of the store, alongside waterproofing agents (powdered additives for concrete and so on). There seem to be a reasonable range of pond sealants, clearly marked as fish safe and usually sold in buckets rather than caulking tubes. These often seem to be bitumen-based, or at least look similar to bitumen.

I see a lot of people recommending not to use the galvanized tanks due to Zinc toxicity. This is for the fish, not the plants correct?

I have a 4ft round galvanized stock tank on my system with gold fish in it. The fish have been happy in there for years. I'm not worried about the fish at this point, but if there is concern for the plants grown on the system then I'll reconsider.

Thanks.

Nope, it is for the fish. I think the factors that may be making a difference in your case are fish species and water ph. Acid water eats metals.