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[Broomies Mate]

Background;

12 Neon Tetra's, 2 young Angel Fish.

46ltr Fluval Edge Tank, with standard pump.  3 Stage filtration (Sponge, Carbon and Bio).  Carbon replaced a week ago, sponge squeezed in tank water weekly, Bio never replaced.

Plastic plants with a fair amount of algae.

Gravel Substrate - Replace a cup-full each week with 'deep clean'.

Water changes:  1/4 water change mid-week, 1/3 water change on Saturdays.  Water test every Sat before the deep-clean - All readings perfect - Occasionally get slightly higher readings of Nitrate, but nothing to worry about. (as far as I know).



OK, now.  Early this morning, had a look into the tank and all seemed ok.  My wife got home from work in the afternoon and 4 of the Tetra's were dead.  She fished them out.

I get home from work and another 4 are looking terrible.  ALL the fish are at the surface gasping for air?

I immediately do a water test using API Master Kit and find Nitrite levels are off the scale, as are Nitrates.  Ammonia is zero.  During an emergency 50% water change, another 4 of the neon's give up the fight.

What could possibly cause this?  Nobody is here during the day, nothing has changed.  Temperature is at a constant, measured by both the in-tank thermometer and my kitchen meat thermometer.

After the water change, the fish seem a little more settled (less gasping) and are settled lower in the tank (as they usually are).

Please help.... Any suggestions as to why this has occurred?

[tunnie]

How old was the water?

[Entwood]

Ammonia (fish wee, poo and uneaten food) is converted to Nitrite by bacteria in your filter system. Nitrite is then converted to nitrate by different bacteria in the filter system.

Ammonia and nitrite are lethal to fish (ammonia it depends on water temp and hardness just how lethal), nitrate is non-lethal but encourages algae growth.

Sounds to me like the nitrite eating bacteria have either been washed out on a filter wash, or have died for some other reason ... is the filter flowing plenty of water ?? not blocked ??

Emergency water changes of 25% every day but do not touch the filter medium .... leave the filter running and it SHOULD reestablish the bacterial colonies .. will take a week to 10 days.

Check ammonia, nitrite, nitrate levels daily before the water change .. ammonia should stay low, nitrite should fall due to water changes, nitrate should slowly start to rise indicating the colony is regrowing.

Don't wash all the filters out at the same time .. ever .. all you do is wash away the bacteria. My tank has 4 filter sponges.. I wash one a month .. no more .. ever. 

[Vamps]

I think you may be doing too many water changes, ours 130L tank gets about a 20% water change every 2 or 3 weeks...

How old is your set up? it took us months to get it right.......

That said we have had 4 newly introduced Platty's simply disappear over the last couple of weeks......

[Broomies Mate]

The tank is under a year old.  I did a 3 month Fishless cycle.  After 6 weeks, the readings were consistent, but I wanted to make sure before adding fish.

The 12 Tetra's were added 3 at a time over a period of a month.

I NEVER wash any of the filter media - I only squeeze the crap out of the sponge filter (once a week) in tank water...... It never gets 'cleaned'.  The carbon gets replaced every 4 - 6 weeks and the Bio remains untouched.

I have a 'pre-filter' on the pick-up tube (this is purely to stop small fish getting sucked though the plumbing).  That again gets a squeeze and rinse in tank water once a week.

Until today, I have never had a problem... The only fatality I have had is a fish who jumped out of the tank (The Fluval Edge is an odd design).

[Entwood]

The tank is under a year old.  I did a 3 month Fishless cycle.  After 6 weeks, the readings were consistent, but I wanted to make sure before adding fish.

The 12 Tetra's were added 3 at a time over a period of a month.

I NEVER wash any of the filter media - I only squeeze the crap out of the sponge filter (once a week) in tank water...... It never gets 'cleaned'.  The carbon gets replaced every 4 - 6 weeks and the Bio remains untouched.

I have a 'pre-filter' on the pick-up tube (this is purely to stop small fish getting sucked though the plumbing).  That again gets a squeeze and rinse in tank water once a week.

Until today, I have never had a problem... The only fatality I have had is a fish who jumped out of the tank (The Fluval Edge is an odd design).

That black gunge is full of bacteria which you are washing away !! If you are getting that much particulate matter you may well be overfeeding ?? What you could try is a fine filter mat right on the top of the filter pile to collect the particulate matter and leave the main filter pads to the bacteria .... I use Juwel PolyPads on the top, wash them out twice a week and chuck monthly ...

Your main filters SHOULD be biological filtering, not mechanical filtering ..

[Vamps]

The tank is under a year old.  I did a 3 month Fishless cycle.  After 6 weeks, the readings were consistent, but I wanted to make sure before adding fish.

The 12 Tetra's were added 3 at a time over a period of a month.

I NEVER wash any of the filter media - I only squeeze the crap out of the sponge filter (once a week) in tank water...... It never gets 'cleaned'.  The carbon gets replaced every 4 - 6 weeks and the Bio remains untouched.

I have a 'pre-filter' on the pick-up tube (this is purely to stop small fish getting sucked though the plumbing).  That again gets a squeeze and rinse in tank water once a week.

Until today, I have never had a problem... The only fatality I have had is a fish who jumped out of the tank (The Fluval Edge is an odd design).

Should you be doing that? my carbon filter, between 2 sponge filters gets rinsed but has not been replaced in years, this is what was advised years ago. I have 2 large filters in the tank, I no longer used the internal system in the lid, a pain to clean, the second filter was added when I stopped using the internal one.

I have water testing kit but rarely use it these days, as the tank is very established with many of the fish 6 or more years old, I have several generations of Plecs cos they keep having a baby, only ever seem to be 1 the rest must get eaten

[Broomies Mate]

Should you be doing that? my carbon filter, between 2 sponge filters gets rinsed but has not been replaced in years, this is what was advised years ago. I have 2 large filters in the tank, I no longer used the internal system in the lid, a pain to clean, the second filter was added when I stopped using the internal one.

I have water testing kit but rarely use it these days, as the tank is very established with many of the fish 6 or more years old, I have several generations of Plecs cos they keep having a baby, only ever seem to be 1 the rest must get eaten

When the Carbon gets 'used' it becomes 'full' then release crap back into the tank. 

The carbon filter in my tank is very small (all the media is small due to design).

It is (I believe) recommended to replace active carbon every 4-6 weeks.

Of course, I am all ears and am willing to take on-board any conflicting advice.

[Entwood]

I have never used carbon at all, and only been keeping tropicals 40 years  Don't see many carbon piles/filters when snorkling 

On a more serious note, the carbon is supposed to remove harmful dissolved substances .... I prefer to try and ensure that such stuff does not get into the tank, and a weekly 25% water change will remove any such stuff anyhow IMHO

I think you are overcleaning TBH ..and killing off the stuff that should be working for you .. bacteria ..

[Broomies Mate]

I have never used carbon at all, and only been keeping tropicals 40 years  Don't see many carbon piles/filters when snorkling 

On a more serious note, the carbon is supposed to remove harmful dissolved substances .... I prefer to try and ensure that such stuff does not get into the tank, and a weekly 25% water change will remove any such stuff anyhow IMHO

I think you are overcleaning TBH ..and killing off the stuff that should be working for you .. bacteria ..

I think you may be right, on both subjects.  For the Carbon, I have been advised to just stick another sponge or bio in it's place.  The Carbon makes the water so crystal though.

As for over cleaning, that's my OCD I'm afraid and something I will have to stop it seems. 

I guess, because it is such a small body of water, any small changes will make a massive effect.

Thanks for the advice - I'm kicking myself now.

[Vamps]

Should you be doing that? my carbon filter, between 2 sponge filters gets rinsed but has not been replaced in years, this is what was advised years ago. I have 2 large filters in the tank, I no longer used the internal system in the lid, a pain to clean, the second filter was added when I stopped using the internal one.

I have water testing kit but rarely use it these days, as the tank is very established with many of the fish 6 or more years old, I have several generations of Plecs cos they keep having a baby, only ever seem to be 1 the rest must get eaten

When the Carbon gets 'used' it becomes 'full' then release crap back into the tank. 

The carbon filter in my tank is very small (all the media is small due to design).

It is (I believe) recommended to replace active carbon every 4-6 weeks.
Of course, I am all ears and am willing to take on-board any conflicting advice.

Might have to look further into that, also I have had other carbon filters previously, this one is the same 'area' and fits in a sandwich between 2 sponge like filters the newer filter is only sponge like filters, each filter is capable on it's own of cleaning more than the size of our tank. The newer of the 2 is a bit of a bugger though as you can not physically remove the filters without some crap falling back into the tank, so may soon be replaced.....

[JWDF]

Sorry if i've missed reading the posts.

But what about the water PH ? 

[the alarming man]

i am with vamps on this one...you shouldnt do too many water changes and do you use a treatment for the new water??? (like easy life) it is designed so the new water does not put undue stress on the fish,and as for a water test kit..i do have one but couldnt tell you where it is...and when cleaning the filter you should not change the charcol as regular as that....just wash it through with tank water....tbh you should only be changing upto 5 % of the medium at any one time

[ozzycat]

whats your water temp it should be around 23-25 degrees any warmer would cause the problem whith the fish

[hercules]

i agree with the over cleaning and tbh i would look for cardinal tetra rather than neon as they dont suffer from tetra disease