[fishscale]

All the fish in one of my 10 gallon tanks just died. Ammonia and Nitrite 0, Nitrate 5 ppm, pH 7.4, everything seems normal. I did a water change this afternoon, and I'm guessing that's what did it. I forgot to do a 20% water change last week on the tank, so I'm wondering, is it possible that CLEAN water killed the fish because they were not accustomed to it? I added the water rather quickly because I was in a rush.

 

[KDahlin]

Could you have forgotten the dechlor/dechloramine?

 

[fishscale]

No, I used Ammo-Lock on the new water. However, this was a 50% water change and I did it really fast (basically dumped it in). The tank's been running for a little over a year, and while I'm not really happy about the fish dying, I guess it will let me start over when I set up my 55 gallon. It was my first tank, and I threw a bunch of random tetras in it before I knew about schooling (and that they were best kept in groups).

 

[fishscale]

Two other things occured to me: I got the water this tank from a different faucet than I usually do. I don't think the water from this faucet is deadly, since I use that faucet for my two other tanks, but this is the first time I've used that faucet for this tank. Could it be something in the water that the fish weren't used to?

Also, I have a filter on the faucet that I usually get the water for the tank in question.

 

[Storm_Rider]

Maybe the stress from a 50% water change and a sudden temperature shock cauesd their demise?

 

[Gatekeeper]

I would lean on the temperature shock as mentioned by Storm Rider.

Better to take your time, or not do it at all.

 

[turbosaurus]

Unless you ran straight cold water into the tank (or 100% hot)- I don't think the temperature did it. You'd probably need a minimum 15 degrees of temp difference - probably more like 30 on a 50% water change to kill the fish outright. 15 degrees on half the water would only change the tank itself 7.5 degrees- that will stress your fish, but won't kill a healthy one.

Its not that easy to kill a healthy fish.

 

[bulrush]

I did a 30% water change on a 20g tank with a ghost knife fish in it. I can tell you I'm pretty certain the water temp difference was only 10 degrees F, and he died within minutes.

So temperature will shock certain fish but not others. A 10 degree difference might kill some but not others.

 

[LS6 Tommy]

I had a 6* temperature drop during a WC shock my fish once to the point where they were just rolling around in the curent like leaves. I didn't lose any, but it sure looked bad for a while. Ph shock will do it too.

Tommy

 

[turbosaurus]

I did a 30% water change on a 20g tank with a ghost knife fish in it. I can tell you I'm pretty certain the water temp difference was only 10 degrees F, and he died within minutes.

So temperature will shock certain fish but not others. A 10 degree difference might kill some but not others.

Dude, that isn't what killed your fish. lets say your temp was 76 degrees, if you remove 30% of the water, its still 76 degrees, now add back that 30% with water at 66 degrees- your new resulting average temperature is 73. NO way a three degree drop in temperature killed a healthy fish. No way. I do that on my community tanks ON PURPOSE to encourage the coreys to spawn and not a single fish has ever minded.

Now if you dropped the whole tank by 10 degrees- that's a very different story. If you started at 76 degrees you'd have to add 6 gallons of water at 43 degrees to bring the average temp down to 66. That's water 30 degrees lower in temp and about the same temperature as the inside of your refrigerator- and that would probably do it.

If the fish was already sick or stressed from other factors temp change can contribute, but by itself its got to be WAY WAY off for temperature shock to kill a fish.

 

[crazie.eddie]

I would have to think it's due to the large water change, due to maybe a rapid temp change and chlorine/chloramine's. Most dechlorinators work fast, but not fast enough, especially if you just dump the water in. For large water changes, it's usuallly advisable to use aged, dechlored, heated water for WC.

 

[fishscale]

figured it out, pH.

I had the dechlor in for about an hour when I changed it. The two faucets have very different pH's, not sure but it might be because of the filter on the tap.

If your tap water's pH is too high, what do you do about it? And what if you have hard water? (I'm sure this is somewhere, but I need to go to work now)

 

[ILuvMyGoldBarb]

That will do it.

Just for the record, there is no way that a 50% WC alone will kill your fish, there has to be another factor in it. I do 90% WCs twice a week on my Discus growout tank and it doesn't bother them in the least, but my pH is steady and the temperature difference is only 2 or 3 degrees at the most.

There is one other factor to consider. The recommended dosing for dechlorinator is based on standard chlorine/chloramine levels in municipal water. Many municipalities will actually add a little extra to their systems immediatly after a drought followed by a very heavy rain. If this happens your standard dosing of dechlor may not be 100% effective.

 

[crazie.eddie]

figured it out, pH.

I had the dechlor in for about an hour when I changed it. The two faucets have very different pH's, not sure but it might be because of the filter on the tap.

If your tap water's pH is too high, what do you do about it? And what if you have hard water? (I'm sure this is somewhere, but I need to go to work now)

It is kind of strange 2 faucets would have different pH, but the filter would make a big difference in water chemistry, especially the pH. I missed the part about the filter.

How high is your pH? I had water at a pH of about 8.0 and fish did well, even for neons/cardinals, angelfish, loaches, which I had at the time.

Just for the record, there is no way that a 50% WC alone will kill your fish, there has to be another factor in it. I do 90% WCs twice a week on my Discus growout tank and it doesn't bother them in the least, but my pH is steady and the temperature difference is only 2 or 3 degrees at the most.
/QUOTE]

If you use WC straight from the tap, your a very lucky person, becuase I know allot of people who perform that large of a WC only from stored water containers (aged, dechlored, & heated).

 

[bcreque]

I do weekly 50% water changes on my 10 gallon straight from the tap, and dose slightly over the recommended dosage of Prime and have never had an issue. Granted, I am fairly careful about water temperature.

 

[fishscale]

It's because we have a really old house, and two different plumbing systems. Yeah, I know, it's retarded, but so is our wiring. One pH was about 7.4, the other was almost 8.0