Backyard Aquaponics
A place to discuss aquaponics

I have read all the horror stories about zinc toxicity from galv tanks and was wondering what the consensus would be on galv weld mesh as a tank cover? The school system is going to have a central beam across the tank that two hinged semi circular covers will hang off to cover the safety issues of primary kids around a 5000 litre tank and to help prevent fish theft. I have a design in mind and was going to use galvanised 100x100 weldmesh over a galvanised 30x30 square tube frame. Reading about the galvanised tanks has got me thinking that we might have to fork out the dollars to make it out of stainless tube and mesh as it needs to last years and I have no confidence in powdercoated steel around water.

Although the lid will not sit in the water, the tank will be in the open so any rain that hits the mesh will drip down into the tank.

If you can do it... go the stainless tube & mesh... or perhaps even the aluminum tubing...

Safer, and longer lasting... although as you say... the only real exposure is from rain... which is a bit different to having fish actually swimming in a zincalume tank....

Can you paint it with an enamel paint. Or rubber paint. Concrete mesh is another way but it will rust unless painted also. But paint would stick to it easier than gal.

I'm worried about using rain water off a zincalume roof as my wife has killed (skinned) fish with it in an aquarium. However I do have a weldmesh cover over my sump tank. The hoops for my tunnel house are made out of galv tube.

IMO, I reckon the amount that would leech of during rain, would be negligible and may even be of benefit, as zinc is a trace element.

negligible yes, however everything's cumulative unless plants or fish absorb it.

Should people look at water changes over time to bleed off anything harmful that may accumulate in a system. My saltwater tank has good water and gets topped up with bottled water but I still like to swap out a little water every now and then. And in the larger sysem I can divert water through a sprinkler in the front yard. Even if its just a practice that is done between croping.

I think they do absorb some: it is a vital nutrient. The big issue is having it submerged in acidic AP water and disolving a toxic amt... I'm guessing it would be ok as a cover.

Trouble is Duff the water you put in is likely to have stuff in as well. Plants, slimes algae and all the other things in the water will use nearly all metals and minerals. Personally I wouldn't bother. Marine and freshwater tanks have to have water changes because there is no (easy) way to get rid of excess chemicals esp nitrates and to a degree phosphorus.

Was thinking more of what trace comes from the fish food. If its made from fish meal then it could contain mercury.

If you want to be cynical about it, you'r the top of the food chain in your system. You eat the fish and vegies and replace them. You'r more likely to get poisioned from the other stuff you eat.

Love being on the top of the food chain.