Lead weights used in aquaria

[mummymonkey]

I've used lead for various uses in my aquaria over the years. For holding down spawning mops, plants etc. I'm not alone as lead has been used all over the world in the aquarium industry for decades.
Now I'm being told this is bad for my fish. I said it was safe and was asked for proof! "How do you know your fish didn't die of lead poisoning?"

Do I need to throw out all my lead weights?

[CaveDave]

I think its not likely that is a problem, but some lead could be leaching out.

You could coat the weights in epoxy or some other plastic (there is a kind for dipping tools in that might work).One brand is plastidip. (http://www.plastidip.com/consumer/index.html)

Or you could cast them from Bismuth, now sold as shot for waterfowl hunters, and easy to melt.

Cheers,
Dave

ETA: Any plastic used I would let have a long "cure" time in a warm place to drive off any solvents or monomers.

[mummymonkey]

Okay thanks for that but it was really a rhetorical question. I'm trying to find out if the lead really poses a problem for fish or not.

[luchog]

Okay thanks for that but it was really a rhetorical question. I'm trying to find out if the lead really poses a problem for fish or not.
It depends on the composition of the lead.

But yes, ultimately lead is toxic. Using lead weights in the wild isn't really that big an issue, since the amount of lead compounds released into the water won't be distinguishable from existing environmental levels. However, in a tank, the concentrations keep building until they reach toxic levels. Frequent large-volume water changes will help, but that will only slow the build.

If you're going to use lead in the tank, it's highly recommended that you seal it with a potable-water-safe epoxy or similar coating.

[luchog]

ETA: Any plastic used I would let have a long "cure" time in a warm place to drive off any solvents or monomers.
It's a very bad idea to use any plastic or rubber compound that is not specifically rated for aquarium or potable water use, as the vast majority of them will continue to release compounds, in some cases for years, that are generally toxic to fish and (especially) aquatic invertebrates.

[mummymonkey]

It depends on the composition of the lead.

But yes, ultimately lead is toxic. Using lead weights in the wild isn't really that big an issue, since the amount of lead compounds released into the water won't be distinguishable from existing environmental levels. However, in a tank, the concentrations keep building until they reach toxic levels. Frequent large-volume water changes will help, but that will only slow the build.

If you're going to use lead in the tank, it's highly recommended that you seal it with a potable-water-safe epoxy or similar coating.Do you know what level is toxic for fish? Also do you have an idea how long a piece of lead would have to be in a tank for this level to be reached?

[Dogdoctor]

If you do water changes like you should then the amount of lead should be minimal even if there is some leaching. The length of time for lead to reach toxic levels is related to the acidity of the water. I don't know what the toxic level might be but here are some safe levels 0.01 mg/L in soft water, 4.0 mg/L in hard water (this is for salmonids but should be somewhat similar in other species)

[CaveDave]

If you do water changes like you should then the amount of lead should be minimal even if there is some leaching. The length of time for lead to reach toxic levels is related to the acidity of the water. I don't know what the toxic level might be but here are some safe levels 0.01 mg/L in soft water, 4.0 mg/L in hard water (this is for salmonids but should be somewhat similar in other species)
As a vet you may know this: isn't lead stored for long periods in the tissues? Such that exposure vs time would be important?

Just asking.:)

Dave

[richardm]

It seems hard to imagine that it's a major problem. People have used lead pipes for drinking water for decades, and some people still do. In the UK lead hasn't been used in new homes since 1970, but there hasn't been a desperate rush to remove all the lead pipes that already exist. Unless fish are particularly sensitive to the stuff - but since you haven't noticed them dying off in droves (and neither did I when I kept fish in tanks containing lead) my assumption would be that it's not really much of an issue.

[MRC_Hans]

Metallic lead is very difficult to absorb. If your lead weights don't show signs of corrosion, I would say there is no problem. Also, lead is mostly a problem high in the food-chain, and since I assume you feed you fish with fodder coming from the outside (as opposed to let them feed on themselves), they are all on the first rung on the local food-chain.

I always used stones, though.

Hans

[Stitch]

I'm guessing you're keeping fresh water fish rather than marine, where the salt water is likely to make a difference. Most marine keepers use Milliput for holding coral frags etc on to rock. It seems to be reef safe and best of all it sets underwater.

[Dogdoctor]

As a vet you may know this: isn't lead stored for long periods in the tissues? Such that exposure vs time would be important?

Just asking.:)

Dave
That is true lead and perhaps why I can only find safe levels and not toxic levels since duration of exposure would be the deciding factor often.

[apocalypse]

It seems hard to imagine that it's a major problem. People have used lead pipes for drinking water for decades...

Just ask the ancient Romans if lead pipes caused any problems...

http://www.unrv.com/economy/lead.php