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Discussion Starter · #1 ·
Recently I've been having at least one RCS die after topping off the water in my 10g NPT (which I've had for about 3 months), so I bought the API copper test kit on suspicion of my tapwater being the culprit.

The test kit revealed that my tapwater has 0 ppm of copper in it. Now imagine my disbelief when my test kit revealed [after multiple trials just to make sure] that the water in my NPT contains .5 ppm of copper! (which I assume to be from the soil since none of the foods I feed contain copper compounds)

It is my understanding that copper is toxic to RCS at .4 ppm, which would explain why I've never seen any shrimplets despite numerous females being saddled. But this does not explain why many are still alive and that deaths only occur after topping off the tank w/ new water.

The booklet that comes with the test kit states, "This test kit reads the level of total copper (free and chelated) in ppm". What I got from Ms. Walstad's book is that chelated metals are less toxic and are far less likely to be absorbed by aquatic animals and plants.

Is it safe to assume that most of the copper in my NPT is chelated since I use a dechlorinator w/ chelating compounds in it (Tetra AquaSafe), the tank has had 3 months to build up DOCs, and my pH is 8.2? And even if most of the copper is chelated, couldn't that level of copper still pose a problem for invertebrates?
 

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I also have copper in my tap water, so I've done a fair bit of reading about it.

It is my understanding that even chelated copper is dangerous to invertebrates. It is also my understanding that they can't cope with anything like 0.4ppm of copper, more like 0.02ppm is lethal. I'm surprised you have any shrimp left. Where did you see that 0.4ppm figure?

What kind of soil do you have in your tank? I'd be surprised if potting mix had that amount of copper in it, but I don't really know. I guess you can't tell at all what is in soil dug out from somewhere.

Chelating stuff in dechlorinator can't cope with that level of copper, as far as I know. They cope with trace amounts, but not large amounts like that (or like the 0.5ppm in my tap water).

Have you tested the tap water from the same tap you fill the aquarium from? Have you tested it at different times of the day?

One thing I learned about copper is that it varies over the day, depending on how much water has been through the pipes recently. So if you test it after the water has been running, you should get a lower result. The worst time should be first thing in the morning, when the water has been sitting in the pipes all night. It's also seasonal, and usually worse in warmer weather, apparently.

Hope that helps. If you find out anything more about copper, please post it, as I am also interested. There doesn't seem to be very much concrete information out there, that I could find.
 

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Discussion Starter · #3 ·
I've actually read all kinds of different numbers on this and other forums stating at what ppm Cu is toxic to RCS, the highest of which was .4. I too thought it was much lower but the fact that I have around .5 ppm of copper in my tank and still have shrimp led me to believe that .4 might be closer to the actual lethal levels.

The soil I'm using is the cheap Home Depot stuff in the red/white bag (I believe it's called EarthGro) that I know other ppl on APC have used before (though I'm not sure if anyone has had success using it in NPTs containing invertebrates).

The tap water I tested was as close as I could get to water I'd use to top off - I let the sink run for a min (not on hot) during midday. I'm wondering if adding a large dose of dechlor to my tank will detoxify the copper even more, tho I'm not sure if adding excess dechlor would create more of a problem than what I'm faced w/ now.
 

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There are lots of variables here. Thus, you need to carefully evaluate your situation before drawing conclusions.

It sounds like your tapwater could be the culprit, since you say that when you "top off" the tank, the shrimp have problems. Nothing like death to provide evidence! Aquarium test kits are frequently unreliable, and the copper content in tapwater can vary widely depending on whether water pipes are recently flushed or not.

If the soil was the problem (leaching copper into water), a "topping off" should rerlieve metal toxicity, not make it worse. I suspect that soil is not the problem.

Finally, make sure that you mix tapwater with AquaSafe before you add it to the tank. I can't imagine that there's anything in AquaSafe that would harm your shrimp.
 

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Discussion Starter · #5 ·
I will test my tapwater at different times of the day to see if copper readings do indeed show up. I had not considered that topping off the water would actually dilute the copper concentration in the tank, so I'm now convinced that the soil underlayer is not the problem.

I always pour Aquasafe into the container first, and then fill the container up w/ tap water so that the Aquasafe mixes in as the container is filled up. Might adding more Aquasafe directly to my tank reduce / detoxify the current copper level?
 

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Discussion Starter · #7 ·
I just wanted to post an update. Despite what I believe to be a fairly high level of copper in my tank, the actual cause of the RCS deaths after topping off seems to be due to nitrites in the tapwater. I am fairly new to the area and never bothered to test the tapwater here for nitrites until my RCS started dying. I tested somewhere between .25 and .5 ppm of nitrite out of the tap, and verified this w/ others in my area via a local fish forum just to make sure my test kit is accurate. I have since switched from Aquasafe to Prime since it claims to detoxify nitrite. None of my RCS have died since the switch to Prime. Lesson learned: don't assume your tapwater parameters are the same in every part of the city lol
 

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Discussion Starter · #9 ·
Thanks very much for your input helenf and Ms. Walstad. Interestingly enough, the nitrite problem in the tap has since subsided for some reason, and I managed to dig up a post on that same local fish forum from over a year back in which someone gave an account of having a "heated" conversation w/ those in charge of the munipal water supply regarding nitrite issues. Apparently in my part of town, nitrites have been reported to be at elevated levels for periods in excess of 10 days at a time, and then return to normal. Bottom line, I am no longer taking any chances and will continue to use Prime.
 

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I'm glad yoiu worked it out.

I think in your position I would be testing for nitrite at each water change. If you can get a test kit for which you can also buy the reagents separately this is cheaper.

(For example, one of the online shops here in Australia sells the API nitrite test for about $15, which is cheapish, but they also sell the nitrite reagent for $3.75, which is excellent. Having bought the test (with colour card, test tube and instructions) once, you then only have to keep buying the reagent refills. Maybe you can find something similar where you are.)

I hope your shrimp stay happy! :)
 
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