Backyard Aquaponics
A place to discuss aquaponics

Help!!! I found my mercury floating on the surface of my tank. All of the mercury has spilled in my tank. What do I do. My fish are still alive, but is this going to hurt my plants. I only have goldfish so eating them is not an issue. But I want to raise tilapia in the future.

Where did the mercury come from - a thermometer or something??

Sounds like your whole system needs to be disposed of responsibly and started over with different aquarium, pump, pipes, media, fish, and plants. I wouldn't touch any of it with a ten foot pole.

Yikes, not good. Turn off the pump. Most of the mercury will be at the bottom of the tank since it's 13 times denser than water. I'd empty the tank after skimming the surface and collect what's on the bottom immediately. Unfortunately it evaporates into air and water and can be bioaccumulated.

Probably what Dave says is the only safe way to go. You could also look at how much mercury was lost into the system and whether it would exceed the 2 ppb MCL for Mercury contamination of drinking water. If its a thermometer I'd call the manufacturer to find out how much mercury is used. When looking for mercury as you clean up, sometimes it will be covered with particulates that cling to the surface tension, it won't always be shiny (Learned this as a kid back when it was cool to play with mercury).

Relax B16

Most thermometer manufacturers use a vegetable oil which is dyed red and responds to temperature in the same way as mercury. This oil is non-toxic and harmless.

The only real danger from a broken thermometer is the possibility of shards of glass remaining in the pool. Typically, any time glass gets into the pool, the pool must be drained to ensure that all glass is removed. However, since most thermometers are made of plastic, this is not usually an issue.

Since you saw your mercury floating, it isn't mercury

Yep....

I also checked the floating glass thermometers because I thought they had little lead weight balls in the bottom of them, but it wasn't lead, it was iron..

Glad to hear they've switched. I'd contact the manufacturer just in case but you probably just got lucky

I'd assumed that somehow the evaporated mercury could form a sheen

I don't know if this was a thermometer or not, I was just guessing. But I haven't seen mercury in anything in a long time. Except if you were to break a CFL bulb over your AP system it would be curtains for the AP system.

There is plenty of Mercury around Dave, I have a max/min Mercury thermometer on my bedroom wall.
However, as pointed out earlier, if the OP says it was floating in his tank, it definitely is not Mercury (13534kg/m^3!), so the topic heading is incorrect

From what I remember of chemistry at uni, Mercury in its liquid form is fairly unreactive as far as being poisoned by it is concerned, I've certainly held it in my hand on several occasions, and I haven't developed mad hatters disease yet Methyl Mercury and other similar forms are much more of a danger. The vapour from Mercury is best avoided too.