Help! Please?

[Aqua-Lou]

Hi all, I thank you in advance for any practical advice.

My tank- 5ft x2ft x2ft
1x Aquamanta EFX600
2x 300w heater
1 long airstone

Last weekend was replace filter media weekend. So I did the usual washing the new media in the old fish tank water to ensure it had the 'good bacteria' in it. I didn't replace all the media, I left the ceramic in and gave it a swill with the tank water.

Anyway, by the Sunday afternoon my fish are all gasping, not at the top of the tank, but whilst swimming around. So panic stations for me, immediately did water test-

Ammonia- 0
PH- 7.5
Nitrite- 0.3
Nitrate- 20

50% water change immediately. Fish seemed to be better. But decided not to feed them for a couple of days to be on the safe side and did daily 25% water changes. Kept up with testing the water and all seemed to settle.
Yesterday I decided to feed mussels, prawn and bloodworm.

Got up this morning and the fish are gasping again! Water test:

Ammonia- 0
PH- 7.5
Nitrite- 0.8
Nitrate- 50

Another 50% water change and the fish have settled again. However, I am now looking at my fish all gasping again. So another water test:

Ammonia-0
PH-7.5
Nitrite- 0.3
Nitrate- 20

I am now very confused and am unsure what to do, do I leave the fish? I am concerned that if I do another water change today I hinder the Nitrogen cycle, any suggestions?

Many thanks, Lou (paranoid and doting fishie parent)

 

[Bugdozer]

Is it possible a contaminant of some kind got in the tank? Things to consider:
Did any soap get into the filter media at any stage?
Did you have handcream on?
Were any small children near the tank while it was unattended?

Also, what species are the gaspers, and are all species in the tank affected equally?

Just had another thought - are you 100% sure the tank temperature is stable? Might your heater or its thermostat be dodgy? Double check with a seperate thermometer.

 

[Aqua-Lou]

Is it possible a contaminant of some kind got in the tank? Things to consider:
Did any soap get into the filter media at any stage?
Did you have handcream on?
Were any small children near the tank while it was unattended?

Also, what species are the gaspers, and are all species in the tank affected equally?

Nothing untoward touched the filter media, I only use the buckets etc that are reserved for fish tank cleaning. No small children/ animals soaps near the tank. I always make sure I have clean hands when doig the tank.

Fish that are gasping-

Clown loaches
2 Oscars
Fire Eel
Black Ghost Knife
Clown knife
Silver dollars

Oscars are now hanging right at the top of the tank.

Temperature is actually too high, just noticed. Its currently at 28 degrees.

 

[fluttermoth]

Washing new media in the old water won't transfer enough bacteria to stop your system going into a 'mini-cycle'; they 'cling on' to the media quite strongly.

Approximately what % of the media did you change? Really you shouldn't change anything except filter floss and carbon, if you use it.

As the bacteria live almost exclusively in the filter, with a small amount on other surfaces, you can change as much water as you like without affecting the cycle.

 

[Aqua-Lou]

Washing new media in the old water won't transfer enough bacteria to stop your system going into a 'mini-cycle'; they 'cling on' to the media quite strongly.

Approximately what % of the media did you change? Really you shouldn't change anything except filter floss and carbon, if you use it.

As the bacteria live almost exclusively in the filter, with a small amount on other surfaces, you can change as much water as you like without affecting the cycle.

I changed the carbon and fine wool and coarse filter pad. But I left the ceramic and also the black balls at the top and the Nitrate pad.

 

[N0body Of The Goat]

With a nitrite reading of 0.25mg/l or worse, I would be basically changing all but enough water to keep the fish submerged on the tank floor i.e ~95% water change.

Gasping at the surface is a classic symptom of nitrite poisoning.

Once you have fish in a tank, the top priority above all else is keeping the water safe for fish, its no good thinking long term about your bacterial colony if there are no fish alive long term because of being poisoned by lethal ammonia or nitrite levels. You need to be prepared to change >75% of the water daily whenever ammonia or nitrite give readings of 0.25mg/l or worse (keeping things simple, temperature and pH do affect things).

 

[Bugdozer]

Sadly I know nothing about your fish types and what they like and dislike. Wish I could be more help.

 

[Aqua-Lou]

With a nitrite reading of 0.25mg/l or worse, I would be basically changing all but enough water to keep the fish submerged on the tank floor i.e ~95% water change.

Gasping at the surface is a classic symptom of nitrite poisoning.

Once you have fish in a tank, the top priority above all else is keeping the water safe for fish, its no good thinking long term about your bacterial colony if there are no fish alive long term because of being poisoned by lethal ammonia or nitrite levels. You need to be prepared to change >75% of the water daily whenever ammonia or nitrite give readings of 0.25mg/l or worse (keeping things simple, temperature and pH do affect things).

I have done a 50% change today and have done every day for a week. I have had this tank for well over a year and a half with no issues as I am very meticulous about keeping it clean and do weekly water changes. I will do whatever it takes to get the water back to perfect again. I have been adised today to not change out too much water as this could also have a negative affect on the tank.
Another test just done-

Nitrite is now below 0.1? confused?

Thank you so much for the help, I really do appreciate it.

Bugdozer, you have been very helpful, much appreciated.

 

[Tolak]

If you've been changing out 50% daily changing out as close to 100% as possible will in no way have a negative effect on anything. Nitrite inhibits the fish's blood from carrying O2 properly, this is the reason for the gasping.

Increased surface motion to keep the O2 level as high as possible will help, basically the nitrifying bacteria have to catch up to the waste products produced by the fish. Doubling up on dechlorinator won't hurt, and will assure that any disinfectants that may slow the growing nitrifying bacteria are removed.

 

[Aqua-Lou]

If you've been changing out 50% daily changing out as close to 100% as possible will in no way have a negative effect on anything. Nitrite inhibits the fish's blood from carrying O2 properly, this is the reason for the gasping.

Increased surface motion to keep the O2 level as high as possible will help, basically the nitrifying bacteria have to catch up to the waste products produced by the fish. Doubling up on dechlorinator won't hurt, and will assure that any disinfectants that may slow the growing nitrifying bacteria are removed.

Thank you, I will carry on with the large daily water changes. Thanks again, for all the help, you are all great.