how to test for stray voltage

[scsinet]

Originally Posted by MaxSmart
http:///forum/post/3107892
Anyway, back on that topic - isn't it possible that the tank (salt water, a conductor, surrounded by glass) could be acting as a capacitor, holding a built-up charge?
Can't see how... a capacitor is two conductors separated by an insulator... if the tank was somehow forming a rudamentary capacitor, I can't see how it would be efficient enough to store a perceptible charge.
Besides... even if it was, then I guess my question would be ... what is "charging" it?

 

[darrinsimon]

Originally Posted by SCSInet
http:///forum/post/3019041
Grounding probes alone without the GFI can make the problem worse.
I have trouble believing that nitrates and phosphates could be zero as well.
Hey SCSInet, what is a grounding probe? (the third prong in the plug, not the neutral or hot?)
Also why can't you believe no nitrates and phosphates? I just checked mine and they were 0, do I need to doubt my test kits? It's a 90G FOWLR with 2 small fish and 12 peppermint shrimp, 80 pounds of LR and 100 pounds of Fuji sand and NO skimmer. (it broke 2 weeks ago, was a piece of junk Typhoon anyway) Two Penguin 300 GPH powerheads and a Magnum 350 with carbon running 24/7. Kits are saltwater master and reef master liquid/test tube type kits. I haven't ever really detected any except at first when it was cycling. Did have some nitrates (5 to 10 PPM) at first but feeding less dropped them to 0.
Sorry for the slight hijack JThomas.

 

[scsinet]

A grounding probe is just what the name implies, it's a titanium probe that is connected to a ground, usually through the third pin of a plug, to ground the water of the tank. They usually also have a resistor built in to prevent a hard fault through the water.
I have trouble believing it because 0.0 is very, very hard to achieve in a closed system. Unless you are constantly running phosphate removal media, it's virtually impossible to get down to 0.0, and unless you are running a deliberate scheme to reduce nitrates such as a denitrator, plenum, turf scrubber, etc, it's vurtually impossible to get 0 nitrates. Sure, you can get nitrates very low and phosphates so low that they are nearly undetectable, but 0?

 

[darrinsimon]

So nearly undetectable is good right? Or should I get different test kits to see if they detect something?

 

[scsinet]

Unless you have a reason to suspect the test is bad, like an algae outbreak, then you can probably trust your readings.
My point to the OP was that if fish are dying and "all tests say there is nothing wrong" then it's time to suspect the tests. IMO stray voltage is blamed for so many problems when it's hardly ever a problem. Even tanks that shock the hobbyists when they stick their hand aren't always a problem for the fish.

 

[maxsmart]

Originally Posted by SCSInet
http:///forum/post/3107998
Can't see how... a capacitor is two conductors separated by an insulator... if the tank was somehow forming a rudamentary capacitor, I can't see how it would be efficient enough to store a perceptible charge.
Besides... even if it was, then I guess my question would be ... what is "charging" it?
You're talking about a plate capacitor - any isolated media can hold a charge (think clouds). My train of thought was that the T5 bulbs might be creating a magnetic field, which could create a potential between the metal of the light (which is ground) and the water.
I ran into something similar when I was in high school - I added an input onto the back of an old phonograph stereo cabinet, leading to a jack on the top (so you could plug in a discman where you can reach it). So, without anything plugged in to either side, it was an isolated wire. I kept occasionally getting a nasty shock when plugging things into it, when it had been sitting for a while with nothing plugged in (to either end). Figured out that the field from the speakers was building up a charge on the wire. Put in a big resistor to dissipate such charges, problem fixed.
The grounding probe will hopefully do the same with my aquarium, assuming it is a similar situation with the charge build-up. However, if the cause of the shocks is actually salt on a wound, it will be a waste of money.
PS - your avatar is hillarious, given the context - brilliant!

 

[maxsmart]

Perhaps I've nailed it - I haven't felt any discomfort sticking my hand in lately. I've had the in-tank heater unplugged. (there are 2 in the sump, which aren't even kicking on because the lighting along is keeping the tank plenty warm) If this continues, I will conclude it was the culprit. I have a grounding probe coming, too. I'm interested to see if that causes any change in my tank's health.