# Catastrophic water change



## idris (7 Jun 2016)

Today I added some fresh water to my tank, and within a couple of hours, all my livestock was dead. (Fish, snails and shrimp.)

Existing 220L tank that's been recently re-commssioned.
Moderate number of plants that have been in for either about a month, or about a fortnight.
New filtration, and all hardscape and glass cleaned with H2O2 or Milton. Anything that had been cleaned with Milton had had several days to dry off and then the tank was well rinsed before it was partly filled with dechlorinated water. 
Akadama from previous instalation, probably with a decent culture of good bacteria.

At the weekend I was a little impatient, and as the water chemistry seemed ok (NO2 = 0ppm, NO3 < 20ppm), I transfered my livestock from a smaller tank I'd set up while the big one was recommisioned. 
All seemed fine for a few days, and last night all the fish looked healthy and were very active. The world was good.

As the tank had only been about 60% filled, today I added some more water.
I used dechlorinator (which was well within it's expiration date) and heated the water to the same temp as the tank before adding it.

Within a couple of hours all the livestock was dead.
The dead fish were all still well coloured, weren't bloated or emaciated, and showed no external sign of infections.
As everything had been fine for several days, and then _everything _died very suddenly, I am assuming some sort of toxin, rather than a pathogen.

I tested the water for NO2 and NO3 again. All was fine.
I took samples of both the tank water, and the untreated tap water to the LFS, along with the dead fish. They tested the water and could see nothing that could explain such a catastrophic crash.

So ...
What now?

Obviously I'm reluctant to restock the tank without knowing what the problem is, and even then only very gradually. 
Do I drain it and refill from scratch?
Do I leave it for a month and hope any toxin can be removed with regular water changes?
If I refill, what can I do to reduce the chances of it happening again?


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## AverageWhiteBloke (7 Jun 2016)

What a nightmare! Has the water people been repairing any pipes nearby?


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## Bugnal1 (7 Jun 2016)

That's definitely a strange one, if you find out what the cause was do let us know.


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## ian_m (7 Jun 2016)

Your dechlorinator was ? Prime ?

Not all dechlorinators will remove chloramine, which is added to water often in emergencies eg water main burst.

Also you test kits will also falsely read negative in presence of dechlorinators, so could have been ammonia poisoning from immature tank.


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## alkm (7 Jun 2016)

Firstly, sorry to hear you lost all your livestock, I know how that feels.

How long had you had the tank running with the new filter and how many fishes, shrimp etc did you add back to the tank?

Did you keep the Akadama from your previous installation submerged and aerated?  I ask this because the bacteria that consume the ammonia and nitrite are aerobic and probably will not survive unless there is oxygen about.

From what you've said I'm thinking either ammonia poisoning or that when you've added the water to fill the tank you have dissolved some H2O2 or milton that has not been rinsed from the top of the tank.  It's possible that you didn't have enough bacteria to deal with the addition of all your livestock in one go. 

You could try an contact the water company and ask if there's been an incident that could have caused this -if nothing has happened then you could rule this out as a cause.

I hope you find out what went wrong.


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## idris (7 Jun 2016)

I did speak to the water company and they have replaced a fire hydrant today, but that was several roads away. Even then the Fluval dechlorinator I have says it deals with chloramines. 

The tank and pump had been circulating for the best part of a month. It had additional plants and water added about a fortnight ago. Possibly a short time, yes, but I don't think that's the problem for a couple of reasons:

A) Whilst the substrate was kept wet, but not aerated (so there is the potential for anaerobic respiration), in that time it managed to sustain several Amano Shrimp and Assasin snails I hadn't spotted when I drained it. They were alive for weeks in the small tank. 

B) The fish all seemed health for the 48+hrs they were in the tank, were active before the new water was added, and were all dead very quickly and shortly after the water was added. 

There were about a dozen fish, 8 shrimp, and I'm not sure how many snails. I did consider a NH4 spike, but all the fish were small (less than 2"), they were in 150+L of water, and again, the fact that all the deaths were in no more than 2hrs, and just after the water was added, does make me doubt that too. That the water tests showed negligible NH4, adds weight to that. I've not heard chloramines effect NH4 tests before, so that's possible, but surely the dechlorinator should have counteracted that. 

If I've ****ed up with the cycling and/or stocking, I'll put my hands up, but the sequence of events strike me as significant. 

Whatever the cause, any suggestions on how to proceed?


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## Martin in Holland (8 Jun 2016)

Any chance you had a sudden CO2 spike?


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## rebel (8 Jun 2016)

This is a very tricky one. Chlorine and Chlroamine wouldn't be that fast. Maybe it's a very acute toxin like cyanide etc that stops respiration quickly. Or maybe lack of O2 or high CO2 as mentioned. It has to be related to respiration and very quick acting as well.

Sorry about your loss.


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## idris (8 Jun 2016)

I don't inject CO2 of use liquid carbon so I think that can be ruled out.
The tank is well oxygenated as there is a spray bar along the length of the tank and its jets were well above the surface constantly causing lots of air bubbles. 

I know cyanide is used to catch wild fish, but I can't begin to think how that could be a factor in the circumstances.


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## alto (8 Jun 2016)

Having experience something similar, I'd suspect the water ... in my case, roadworks were 1-2 km distant, did a water change as normal after driving past the construction, then watched fish die    
The few that survived the night, died over ensuing weeks
I never measured anything unusual


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## rebel (8 Jun 2016)

idris said:


> I know cyanide is used to catch wild fish, but I can't begin to think how that could be a factor in the circumstances.


I meant similar to cyanide. Not cyanide per say. Cyanide blocks aerobic respiration and causes very fast death. Similar to what you saw. I'd be looking for a chemical with similar properties as the culprit as you have excluded all the easy stuff.


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## ian_m (8 Jun 2016)

Sudden fish deaths like you are seeing, in my experience are nearly always due to chloramine being introduced into the water supply due to emergency water main issues. You are supposed to dose double (or more) dechlorinator if you use water with chloramine or suspect you have water with chloramine as chloramine is much "harder" to remove from the water.

My local fish shop had a week where a number of people who bought fish from them, came back a week later complaining all their recently purchased fish had died and also killed all their other fish. This was due to local chloramine dosing due to a major burst water main (was quite an impressive fountain). My water at home went slightly brown due to dirt for a day or two afterwards.

Also chloramine can be broken down, by some dechlorinators (not Prime), into the fish safe chlorine part (usually sodium chloride, common salt) and ammonia and it is the left over ammonia that kills the fish. At normal chloramine dosing the ammonia will quickly disappear in the tank, but when emergency dosing of chloramine occurs there is a massive ammonia spike. I notice Fluval dechlorinator doesn't remove ammonia.


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## dw1305 (8 Jun 2016)

Hi all,





idris said:


> There were about a dozen fish, 8 shrimp, and I'm not sure how many snails. I did consider a NH4 spike, but all the fish were small (less than 2"), they were in 150+L of water, and again, the fact that all the deaths were in no more than 2hrs, and just after the water was added, does make me doubt that too.


Bad luck, I think it was a water issue, rather than a "normal" ammonia spike. 





idris said:


> I did speak to the water company and they have replaced a fire hydrant today, but that was several roads away. Even then the Fluval dechlorinator I have says it deals with chloramines.


That would be my suspicion. They may also have added more NaOH to the water which would have raised pH, and potentially converted NH4+ to NH3. 

Because of the very quick deaths, a possibility is that they also treated the pipes to remove _Asellus. _<"When I lived in Bath we had _Asellus_ in our tap water supply">. 

I think <"they use CO2 to do this now">, rather than an insecticide, but they may still use a synthetic pyrethroid (like permethrin) with a low mammalian toxicity.

cheers Darrel


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## idris (8 Jun 2016)

I shall call the water company again and see if I can ascertain exactly what they put in the ware. 

It's not a crippling amount of money to replace the livestock, maybe £50-£100 but if they have added something that's caused the problem, is there is any chance of compensation, or is it likely to say "tough ***" in their small print?


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## alkm (8 Jun 2016)

Hi again,

If you've ruled out ammonia and nitritie poisoining this leaves 2 possibilities either toxic substances in the tap water or residual toxins form cleaning in the upper part of your tank.

You said you had the tank 60% full of water so potentially you could have had some residual peroxide or milton in the top part of your tank.
H2O2 - I believe fish are quite tolerant of hydrogen peroxide and from what I've read toxicity can occur in the 500 - 1000 ppm range.  As you were presumably using a very dilute solution it is extremely unlikely that this is the cause. Also any remnants of peroxide in the tank would have dergraded quickly.

Milton - This contains 1% Sodium hypochlorite.  Sodium hypochlorite is extremely toxic to aquatic life.  The no effect concnetration is 0.21 ppm which means any concentration above this is likely to be toxic to aquaic life.  However, as your tank has a large volume and the hypochlorite concnetration in Milton is only 1% I suspect that any residues would have been diluted to below 0.2 ppm.

So, excluding peroxide and hypochlorite toxicity the only thing we're left with is tap water toxicity.  Unfortunately, there is nothng you can do about this.   In your position I'd set the tank up again and add some hardy fish to see how they get on.  If you know anybody who keeps fish in your area you could ask them to see if they've also had problems.

Just one more thing - You need to be careful using hydrogen peroxide and sodium hypochlorite as they can react together extremely violently.  Have a look at the  elephant's toothpaste reaction - this uses potassium iodide instead of hypochlorite but it's the same effect.

Anyway good luck setting up again.


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## idris (8 Jun 2016)

Whilst the tank was only partly filled when I introduced fish, I think I'd been pretty thorough rinsing the whole tank before I even put the plants in, so I'd be surprised if that's the cause. I know it's easy to blame someone else rather than want to take responsibility for screwing up, but I can't think how I would have done so. 

I wouldn't usually mix cleaners, which I haven't done in this case, but a useful reminder. I know the risks of chlorine based bathroom cleaners and descalers, and it wouldn't surprise me if an oxidising agent like H2O2 could liberate Cl in the same way. (Though my chemistry is nearly 30yrs old!)

Would you drain the tank and/or go through the cycling again?


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## alkm (8 Jun 2016)

idris said:


> Whilst the tank was only partly filled when I introduced fish, I think I'd been pretty thorough rinsing the whole tank before I even put the plants in, so I'd be surprised if that's the cause. I know it's easy to blame someone else rather than want to take responsibility for screwing up, but I can't think how I would have done so.


I think it's very umlikely that this is the cause but it's good to work through every possibility.



idris said:


> Would you drain the tank and/or go through the cycling again?


Personally, I would drain the tank and rinse with thoroughly with water and cycle again.  I'd try woudl try to contact the water company again before adding any fish to try and undersand what happened.  They may not be forthcoming but if you can find other people that have had the same problem that may help persuade them.  Also. I'd use a conditioner that deals with chlorine and chloramine.


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## zozo (8 Jun 2016)

Nowadays they use plastic tubes and fittings for subterranian piping and the fittings have a kinda plastic(rubber) seal ring, to fit all together and make the tubes and seals slide easily into eachother they need to use lubricants. I've worked a while in the piping industry and very often dish washing soap is used as a lubricant. For us humans not realy toxic and it washes out relatively quickly.. But i guess for aquatic life it aint the most healthy substance to get in the tank.


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## Paulo Soares (8 Jun 2016)

This is hard to read and imagine.. so sorry for your lost my friend.

I don´t know by witch ways in your country you can oblige the water company assume your losses. But i wouldn´t rest and take a slip on it.. i would go to all institutions.

Here in Portugal, these kind of thing is taken very seriouly by our water company suppllier. (City Hall)

Once i was starting a WC and i smell a lot of bleach odor coming from the tap water. So i stoped imediatelly. I filled a great cup of water and record what was happening in the glass Lot´s of effervescence!. Then i present a claim to legal authorities with the video (ministerial agency of health and others) and to the city hall of course.
They answer and apologise that they were doing a special treatment according to something in that day.

So i claim back again to all Health Legal institutes and others that the city hall should previously warn citizens about this matters so that people be aware. And this is what is hapenning nowadays. Everytime the City Hall intends to make something in the tap water circuit they inform the population the day and the hour and time duration time of the interrunption.

I have no doubt that in that day if i did the WC i could kiss goodbye my live stock..

As concerning H2O2 simple forget it. In the past I dose massive and extremely H2O2 in my tank and never had a loss. Tested and tested over and over.

I don´t have any doubts the issue was on Tap Water. All occur after that.

Best regards

Sorry for so many writing errors .. i´m in a rush.


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## Julian (8 Jun 2016)

Is there anything that fish keepers can buy to test for Chloramine, like strips etc?


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## Derek113 (8 Jun 2016)

This is an odd situation. For fish to die so quickly i would assume water quality/chemical poisining is the culprit.

What was the temprature when the water change was done?


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## ian_m (8 Jun 2016)

Julian said:


> Is there anything that fish keepers can buy to test for Chloramine, like strips etc?


Yes is the answer, but as with all test kits reliability and repeatability of hobby grade test kits is not good.

Just add Prime is best you can do assuming chloramine is always present.


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## alkm (8 Jun 2016)

alkm said:


> Milton - This contains 1% Sodium hypochlorite. Sodium hypochlorite is extremely toxic to aquatic life. The no effect concnetration is 0.21 ppm which means any concentration above this is likely to be toxic to aquaic life. However, as your tank has a large volume and the hypochlorite concnetration in Milton is only 1% I suspect that any residues would have been diluted to below 0.2 ppm


Hi, i've just realised I made a mistake on the no effect concentration of sodium hypochlorite. It is 0.21 ppb not ppm and this makes a big difference.  I'll have a look into acute toxic concs when I get chance and back to you.


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## dw1305 (8 Jun 2016)

Hi all, 





Julian said:


> Is there anything that fish keepers can buy to test for Chloramine, like strips etc?


 Measurement is tricky because you have a continual trickle of CL2 and NH3.

It is just a more <"persistent form of chlorine disinfection"> using monochloramine (NH2Cl), the term used is "residual disinfection capability". Chloramine is persistent, and will slowly be hydrolyzed to NH3 (picking up an H+ from the water) and Cl2.

<"Water conditioners like Prime"> work by combining the ammonia into a non-toxic molecule, but it will still be picked up by ammonia tests.

If you have a large plant mass (ideally including floating or emergent plants) and do relatively small volume water changes (with added) conditioner it shouldn't be a problem.

If you add chlorine (Cl2) as your disinfectant it will out gas a long its concentration gradient with atmospheric levels of Cl2, which are extremely low (chlorine is highly reactive, so readily forms compounds NaCl etc). Chloramine disinfection just produces a constant trickle of Cl2. In terms of drinking water the small amount of NH3 produced is irrelevant, but not if you are a fish keeper. 

It is because it is highly reactive and an oxidising agent that chlorine works as a disinfectant (in solution as hypochlorous acid (HCLO) and hypochlorite (CLO-)). 

cheers Darrel


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## Parablennius (8 Jun 2016)

This is the issue with domestic water supply companies. They sell you drinking water, not "fishkeeping" water.


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## alto (8 Jun 2016)

> Sudden fish deaths like you are seeing, in my experience are nearly always due to chloramine being introduced into the water supply due to emergency water main issues.



Absolutely no chloramines in my present area - nor in my roadworks tank disaster.
I often increase Prime dosing during summer months or if there's been heavy rains with flooding as Water Board will add additional chlorine, it's also good to know how close you may be to a chlorine dosing station (in my case not too far, on occasion I've turned on the tap & had to step back  ... I don't water change then)

In case of negative fish reaction post-water change I always begin by adding additional Prime - I use a Python & monitor fish closely during water changes, also keep filter running while refilling tank (I rarely turn filter off)


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## ian_m (8 Jun 2016)

alto said:


> I use a Python & monitor fish closely during water changes, also keep filter running while refilling tank (I rarely turn filter off)


I have heard of people not turning their filter off and untreated tap water killing their filter and fish dying due to massive ammonia spike. Mind you Prime should prevent any ammonia spike.


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## xim (8 Jun 2016)

Julian said:


> Is there anything that fish keepers can buy to test for Chloramine, like strips etc?



I use a chlorine test kit for swimming pools. It will turn yellow when there is chlorine and will be clear without.
I will add a little more de-chlore after it looks clear to cover some misreading.

I've recently switched from Prime to Seachem Safe. With the test kit, I've found that the recommended amount is far too little for the chlorine level where I live. So I'm not surprised anymore why there are reports of fish deaths in aquarium forums from people who use Safe for the first time.

Chlorine level is not static, it can change, especially for areas using surface water where the quality can be very different depending on the time of year which affects the amount of chlorine/chloramine needed to make the water safe.

I also have a NH3/NH4 test kit and used it occasionally. It never gets higher than 1 PPM. So I know what is the baseline.

I don't pray and hope for the best when using a de-chlore product.


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## alkm (8 Jun 2016)

alkm said:


> Hi, i've just realised I made a mistake on the no effect concentration of sodium hypochlorite. It is 0.21 ppb not ppm and this makes a big difference.  I'll have a look into acute toxic concs when I get chance and back to you.



Right, apologies for the confusion earlier.  I've now found a reliable reference.

The no effect concentration for sodium hypochlorite is reported as 0.06 ppb TRC (total residual chlorine).  Assuming TRC refers to the amount of chlorine in sodium hypochlorite then the actual no effect concentration for sodium hypochlorite will be 0.13 ppb.

There is not much data reporting acute toxicity but a lethal concentration is reported as 33 - 60 ppb TRC which would = 70 - 125 ppb sodium hypochlorite - as you can see this is pretty nasty stuff.

So under these assumptions how likely is it that hypochlorite was the problem?  If we use *70 ppb* as the lethal concentration then you need to have at least *15.4 mg* of sodium hypochlorite in your 220 L tank.

Miltons website states that the sodium hypochlorite concentration in their product is *2%*.

Therefore you would need *0.77* mL in *220 L* for a lethal dose.  *It would be good if someone could check these calculations*.

This is not much liquid at all.  Are there any gaps at the top of your tank where Milton could have seeped in to?  If these calculations are correct then my feeling is that it could be possible that the hypochlorite caused the sudden fish death.  There are other factors to consider such as the chemical stability of hypochlorite (it's very reactive) which may mean that it can be ruled out as a cause.


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## idris (8 Jun 2016)

alkm said:


> Therefore you would need *0.77* mL in *220 L* for a lethal dose.


It's about a month since I cleaned (and then rinsed) the tank. Would any Cl not have gassed off in that time?



xim said:


> I don't pray and hope for the best when using a de-chlore product.


I wouldn't say it's just hoping for the best. I've not had anythihng like this  in 15yrs of keeping fish.


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## zozo (8 Jun 2016)

Parablennius said:


> This is the issue with domestic water supply companies. They sell you drinking water, not "fishkeeping" water.



Even that is not the case in some countries, i've been to places where no drinking water came from the tap.. This you had to buy bottled in the store. What came from the tap tasted like pure saltwater..


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## alkm (8 Jun 2016)

idris said:


> It's about a month since I cleaned (and then rinsed) the tank. Would any Cl not have gassed off in that time?


Chlorine would form in the presence of strong acid so it probably would not have gassed off.  The solid form is very unstable but residual amounts may have stayed in solution if there was anywhere for it to seep.  I'm not sure how long the solid form would persist (e.g if the milton evaporated and left a solid residue).


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## idris (8 Jun 2016)

alkm said:


> The solid form is very unstable but residual amounts may have stayed in solution if there was anywhere for it to seep.  I'm not sure how long the solid form would persist (e.g if the milton evaporated and left a solid residue).


You can get white crystals forming round the top of a bottle of Milton. I'm not sure what they are, so I guess this is possible, but as the only nooks and crannies that any of the solution could get to are still about 3" above the water, I'd be surprised if this is the cause.


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## ian_m (9 Jun 2016)

xim said:


> I use a chlorine test kit for swimming pools. It will turn yellow when there is chlorine and will be clear without.


Very very very very very careful. Pool kits shows free chlorine (ie gas) and will not indicate chloramine.


xim said:


> With the test kit, I've found that the recommended amount is far too little for the chlorine level where I live


Be super super super careful, most dechlorinators will influence test kits, especially nitrate & ammonia kits will under read as they bleach the indicator dye. Chlorine test kits will give a false positive due to chloride being produced as by product of dechlorination.

Also, to the other replies, any residual sodium hypochlorite will very, almost instantly disappear once it gets in the tank as it will react with any organic compounds (ie bleaching them). Thus I would say it will be almost impossible to get any significant level of hypochlorite in you tank, which is probably why bleach is the recommended method of cleaning tanks etc. People have returned their bleach regenerated Purigen bags to their tanks, forgetting to rinse and dechlorinate the bleach first, and suffered no fish/plant/tank issues.


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## alkm (9 Jun 2016)

ian_m said:


> Also, to the other replies, any residual sodium hypochlorite will very, almost instantly disappear once it gets in the tank as it will react with any organic compounds (ie bleaching them). Thus I would say it will be almost impossible to get any significant level of hypochlorite in you tank, which is probably why bleach is the recommended method of cleaning tanks etc. People have returned their bleach regenerated Purigen bags to their tanks, forgetting to rinse and dechlorinate the bleach first, and suffered no fish/plant/tank issues.


Please don't take my posts as judgemental in any way and I'm certainly not suggessting people don't use bleach to sanitise their equipment.  I always think it's a good idea to consider all possible root causes when something tragic like this happens.  Given what idris has said I think it is highly unlikely that hypochlorite is the cause but it opinion it was not inconceivable.  Milton will be stable in the absence of organic matter and it could have pooled somewhere.  Also the white crystals that are observed on the top of the bottle are mainly sodium chloride.  If solid forms from evaporation the hypochlorite will co-crystallise with NaCl and this may confer some stability to the solid.

If hypochlorite is suddenly added to an aquaium I agree that it would react rapidly but, dependent on concentration, it would almost certainly effect the aquatic livestock as well.

Anyway, whatever the cause let's hope it doesn't happen to you again idris and once again good luck setting your aquarium up again.


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## xim (9 Jun 2016)

ian_m said:


> Very very very very very careful. Pool kits shows free chlorine (ie gas) and will not indicate chloramine..



I use the OTO type, it measures total chlorine, which includes chloramine.


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## iunknown (9 Jun 2016)

What happened to me recently was that one of my two filters failed.  Basically when both filters are running the tank is saturated with oxygen.  When one fails, there is not as much oxygen available in the tank and the other filter's bacteria sucks the remaining oxygen to toxic levels, killing all the fish.


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## idris (10 Jun 2016)

I've got one, brand new filter that's rated to turn the tank over about 10 times an hour (with its current level of water) and it hasn't stopped. So I don't think that's the issue.


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## dan4x4 (18 Jun 2016)

Its unlikely for a hydrant repair however dependant on the main that the hydrant is on, the water may of been rezoned from another area its possible that the water is fluorodated in the other area. Also when work carried out the parts etc will be sprayed with chlorine, so if you where unfortunate enough, maybe you have drawn the water in with strong chlorine. Although this is unlikely as you will of most likely noticed a strong chlorine smell.

Furthermore if you have iron mains, then rust builds up on the bottom of the pipe work, when the water supply is interrupted it can cause the sediment to be kicked up into the supply. So basically water then has a high iron content, you may not actually notice discolouration unless you have a large volume of water in a white container for e.g. a white bath. However if filling a 10 litre bucket you may not notice the sediment especially if the bucket it coloured.

Sorry to hear that your fish are gone. It may of been something else that we don't know that killed them. Its probably highly unlikely to happen again, but you can add a filter to catch the mains sediment onto your main pipework. However if you do this, its important to make sure that the filter is serviced at the correct intervals.


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