Backyard Aquaponics
A place to discuss aquaponics

Hi there,

Aside from a liner, has anyone researched the safest coating available in the US market?
(Safe to fish, humans, and plants?)

Thanks,
Rebecca

many and varied

Liners can get pricey but quality is worth it. For small items (not normally used in ap), Krylon Fusion for plastics has been used in expensive saltwater tanks (let dry/cure for 48 hours) mainly for coloring tank objects. I wouldn't try to coat an entire tank with it. If part should flake off or get scraped off by fish, then you'd have a part that was no longer coated.

Maybe research liquid electrical tape or plasti-coat (rubber), but again, if it gets scraped off, same issue. This would probably come out pricier than a liner for large areas. Search the web for aquarium results with marine paint. I vaguely remember marine paint having a drawback at some point, maybe degrading after a year or so, don't really remember what it was at this point.

Two part food grade epoxy should be safe once fully cured. I imagine this would get pricey as well for large areas. I've coated my leather renaissance mug using EnviroTex Lite (at craft stores) and used it one season so far and wouldn't hesitate to coat a tank with it (if I could afford that much).

Good luck and let us know what you end up using!

If I had to coat a container I planned to use Sani-tred Permaflex, based on info from other users here on the forum about a year ago:

http://www.sanitred.com/WaterFountain.htm

To clarify, I mean coating for a metal stock tank.

FWIW Permaflex can be used on wood, concrete, or metal.

Someone offered me a 6' round metal stock tank for $45, but I'm beginning to think it would be better to shell out more for a new plastic one to save all the labor involved in figuring out which product to buy*, not to mention the time involved in locating a source and doing the coating application process. Using a liner is simpler, on the whole, but I'm not sure that would save enough money to compensate for extra time acquiring and plumbing it. And again, I'd want to research EDPM safety.

*I'd want to cross-reference coating ingredients--if they can be determined--against toxicity databases. I'm concerned about human toxicity as many of these products have not been evaluated from that standpoint and have ingredients that could leach into water and get taken up by plants and fish and then us hungry beings.

Toxicities of epoxy and other coatings are usually from the solvents before they cure. After curing the only material left is rubber for the polyurethane coatings. If you don't feel comfortable with rubber then it will be a long haul.

Just so happens I do a lot of medical writing. Last month an editor asked me to cover the "Allergen of the Year"--a class of compounds called "thioureaus" that leach out of rubber. A fair number of people get severe contact dermatitis from rubber products, primarily from thioureas.

Over time, I've learned that what we think to be safe can change radically. It doesn't hurt to play it safe.