# Changed Water / Cleaned Filter -- now most fish are dying



## BlondeGecko (Nov 30, 2014)

I have a 92-gallon tank that we just took over maintenance of about 6 months ago, so we are new to maintaining a cichlid tank. We have never had a problem with the fish until today, when I did a 25% water change and cleaned the filter, and now most of the 19 fish appear to be dying. Here are the facts:
- We changed 25% of the water, vacuuming the substrate as we drained the tank
- I didn't add any Prime until I discovered the fish were having problems (didn't really know how important this was). I added about 1/2 capful of Prime, but this again was after the fish were in trouble.
- The last water change was a week ago, with minor vacuuming of the bottom. The last filter cleaning was about 3 weeks ago.
- I have a Marineland C530 canister filter. After bringing down the water level by 25%, I turned off the filter and cleaned it. I rinsed off all of the items (except the balls with bacteria) with tap water. I then replaced the polishing filter pad, then put everything back together, hooked up the filter, and turned it back on.
- I added water back to the tank using our Python, checking temp with fingers to assure that temp was the same as the tank. Again, I forgot to use the Prime until after it was too late.
- Water tests after I changed the water were: 8.0 pH, 0 Nitrite, 0 Ammonia, 10 Nitrate
- I also added a new plastic plant to the tank but rinsed it off before adding it to the water.

What could have caused this massive die-off? Is there anything I can do now to correct it?


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## Dezimir (Nov 2, 2014)

How much chlorine is in the water the tap? How much of a difference in temperature is the tap water compared to the tank water?
Seems like some sort of shock happened. Do you always rinse the filter pads with tap water?

From your water tests it doesn't seem like you had a mini cycle or anything like that. 
Only thing I can think of is water temp and chlorine.


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## BlondeGecko (Nov 30, 2014)

I just tested the water temp using my hand as it went into the tank, and the temp seemed to be the same.

I don't know how much chlorine is in the tap water. My water kit doesn't include a test for chlorine. How do you test that? As for the Prime, should I be adding that as I'm refilling the tank? Do I only treat for the number of gallons I'm replacing or for the entire tank? It says on the bottle to treat for the number of gallons replaced.

I didn't rinse the filter pad before putting it into the filter canister. I have rinsed it in the past but didn't do it this time. Didn't know if I should be doing that.


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## The Cichlid Guy (Oct 18, 2014)

If you're adding Prime directly to the tank, treat for the entire volume of the tank. This is directly from the bottle.

Also, if you're going to rinse anything, I would do it in a bucket of tank water rather than tap water. This will preserve any beneficial bacteria, and avoid introducing trace amounts of chlorine/whatever nasties might be in the tap water. It's good that you did not rinse the bio-balls. :thumb:

Did the fish start looking bad immediately after the addition of the untreated water, or some time later? Was your water test immediately after the water change, or some time later?

It's possible the fish just suffered a massive shock from 20-30 gallons of chlorinated water, but I would test the water again to see if you might have disturbed the bacteria colony. I don't think much can be done to change what has happened, other than continuing to use Prime (for the entire tank volume) and monitoring the levels.


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## Dezimir (Nov 2, 2014)

You can look up your local water treatment plant/municipal on google and there should be a report of what they put into the water. You might see chlorine or chloramines in the list of chemical additives they use and how much. If they are adding it to your tap water that will give you a good idea if chlorine was a major factor here. If they are adding those things or any other heavy metals definitely use prime for every water change.


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## BlondeGecko (Nov 30, 2014)

Cichlid Guy: The fish started looking bad pretty soon after the addition of the untreated water. I tested the water immediately after completing the above changes. I just now did another test and all looks pretty good: 7.8 pH, 0 Nitrite, 0 Ammonia, 10 Nitrate.

By the way, the Prime label says to use 1 capful (5ml) for each 50 gallons of NEW water. Again, wouldn't that mean to add Prime to just treat the 25gal. that I replaceed?


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## chopsteeks (Jul 23, 2013)

BlondeGecko said:


> Cichlid Guy: The fish started looking bad pretty soon after the addition of the untreated water. I tested the water immediately after completing the above changes. I just now did another test and all looks pretty good: 7.8 pH, 0 Nitrite, 0 Ammonia, 10 Nitrate.
> 
> By the way, the Prime label says to use 1 capful (5ml) for each 50 gallons of NEW water. Again, wouldn't that mean to add Prime to just treat the 25gal. that I replaceed?


If you are adding new water directly into the tank, you need to dose Prime for the total # of gallons of the tank, not just for the new water.


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## BlondeGecko (Nov 30, 2014)

Should I be testing my tank water for chlorine to see if I have put in enough Prime? How do I ensure that I have put in enough? We have now added more Prime to treat the total 92gal. in the tank. However, there is no chlorine test in my kit.


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## The Cichlid Guy (Oct 18, 2014)

You can find chlorine tests at most of the big box pet stores, although I don't know if they have anything besides test strips. If you've used two capfuls of Prime in the tank, you should have enough. You can safely use more than the recommended dose. I don't really think you need to test for chlorine in the tank (assuming you have now dosed Prime based on the entire volume), although it couldn't hurt.

I don't mean to beat a dead horse, but here are the directions from Seachem's website/the bottle:

"Use 1 capful (5 mL) for each 200 L (50 gallons*) of new water. This removes approximately 1 mg/L ammonia, 4 mg/L chloramine, or 5 mg/L chlorine. For smaller doses, please note each cap thread is approx. 1 mL. *May be added to aquarium directly, but better if added to new water first. If adding directly to aquarium, base dose on aquarium volume.* Sulfur odor is normal. For exceptionally high chloramine concentrations, a double dose may be used safely. To detoxify nitrite in an emergency, up to 5 times normal dose may be used. If temperature is > 30 °C (86 °F) and chlorine or ammonia levels are low, use a half dose."

Basically, if you pre-mix your new water in buckets, you can add enough Prime to treat your new water, but if you're adding the water directly to the tank, there is no way to specifically treat the chlorinated water, therefore you have to use enough Prime to treat all of the water in the tank.


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## BlondeGecko (Nov 30, 2014)

Thank you! I didn't see the sentence about adding directly to the aquarium. We have now added a total of 2.5 capfuls of Prime and the fish that didn't die are now swimming around and looking much better.

So in reflection, we are still surprised that replacing 25% of the tank and not treating the water with Prime would have killed fish. It looks like we lost at least 3 fish. I will know more tomorrow as I take a count of the remaining fish. Thanks for your help!


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## Austinite (Jul 27, 2013)

My tank is 110 gallons and I use 3 caps of Prime with every water change, I pour the Prime right into the tank as I am filling it. I typically change out 40% of my water every week. I really think the untreated tap water was the culprit here; the water added into the tank, and the water used to rinse the filter. I also rinse my filters & media in a bucket full of tank water, never water from the faucet. Sounds like the fish are looking better and hope you won't have any more losses, so sorry that happened to you!


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