Oxygen Level Question

[nigsy]

Hi all,

My first post (hopefully of many, not all with probs though!).

A bit of history first. I am not new to keeping tropical fish. I have had a small 90litre setup for about 24 months.
Feeling confident, and with an understanding of how tanks work and what kind of fish I am comfy with, 3 weeks ago I bought a much larger tank. A fluval 260 (260 litre).
All the water from the 90 liter tank was moved to the new tank. Also my existing filter setup (a fluval 350 external filter), I simply switched across, with all the media intact. The pump was inactive, but full of water for 30 mins maximum. I filled the new tank up, introduced my existing fish to the new tank and all was good.
Last week, 2 weeks after set up, I checked the chemistry and all was good, so I went out and bought some more fish. Again introduced them, didn't loose any until today.
I came down this morning ( this is 3 weeks after set up), and all the fish are gasping at the surface for oxygen, even worse all 3 of my shrimps (9 months old and the most reliable algae eaters around) were dead on the bottom of the tank.
Some info to help:
Tank surface area= 800 square inches
Nitrates = 0
Nitrites =0
Ammonia =0
Ph = 6.6

Fish in tank:
5 harlequins
6 phantom tetras
6 white tip tetras
1 Black stripe tetra
2 albino cory
2 dwarf gourami
(and there were my 3 shrimp)

My questions are:
Obviously this is an oxygen problem, but why has this suddenly happened?

How can I fix it?

Is there a way of measuring dissolved oxygen rates?

As it's to late to save the shrimps, a general question about them. Do they have gills? did they suffocate because they can't swim around at the surface?

I have done a small water change this morning to bump O2 levels back up, and the fish seem happy again, but do need a permanent fix.

Cheers, in advance.

 

[Miss Wiggle]

oxygen is very hard to detect level of, fish gasping at the surface is usually the first sign.

have you checked the temp of teh water, it could be that the filter has malfunctioned and stuck on 'on' so the tanks heated up too high, as water heats up it holds less oxygen which can cause ifsh to struggle for breath and gasp at the surface. just a possibility anyway so check the temp of the tank and that the heater is still working correctly.

it's slightly odd that nitrate is at 0, what test kit are you using (make and model), when did you take those test readings?

did you do anything in the last day or two that could have gone wrong, any routine maintenance, water changes etc?

best way to get oxygen into the water is to create surface agitation using your filter, to either move the filter or adjust the water level in the tank so that the output from the filter makes waves across the tank, if you can set it so that the output from the filter is above the water's surface and falls onto it that gets the best oxygenation (it's noisy and makes you need the loo but just do it as a temporary thing for the day to get O2 back into the tank).

 

[Athena]

Also, have you double-checked that your old filter is now compatible with the much larger tank? A larger tank might mean you need to upgrade to a more powerful filter - or even have two - one at each end of the tank.

Yes, as mentioned by someone else, make sure that your filter nozzle is sitting just at water level in order to create turbulance across the surface. If your filter isn't creating much turbulance then you can add an air stone. If you position the airstone flow so that the bubbles rising clash with the stream of water from the filter nozzle, this will cause extra turbulance and the air bubbles will be "bounced" around allowing more gases to escape from the tank water.

Athena

 

[nigsy]

oxygen is very hard to detect level of, fish gasping at the surface is usually the first sign.

have you checked the temp of teh water, it could be that the filter has malfunctioned and stuck on 'on' so the tanks heated up too high, as water heats up it holds less oxygen which can cause ifsh to struggle for breath and gasp at the surface. just a possibility anyway so check the temp of the tank and that the heater is still working correctly.

it's slightly odd that nitrate is at 0, what test kit are you using (make and model), when did you take those test readings?

did you do anything in the last day or two that could have gone wrong, any routine maintenance, water changes etc?

best way to get oxygen into the water is to create surface agitation using your filter, to either move the filter or adjust the water level in the tank so that the output from the filter makes waves across the tank, if you can set it so that the output from the filter is above the water's surface and falls onto it that gets the best oxygenation (it's noisy and makes you need the loo but just do it as a temporary thing for the day to get O2 back into the tank).

Make of the testing kit is aquarium pharmaceuticals inc.
I did the water test this morning, before adding fresh water.
I have adjusted the outlet on the filter to point at the surface. The outlet jet on the pump is about 15cm below the surface, so at full speed is only able to make ripples on the surface as opposed to cascading effect. Should I lower the water level temporarily? (It's going to mean taking about 100 liters out of the tank, nearly a 50% change)

I have found out that one of the fish we bought has white spot, and unknown to me, my wife added a white spot treatment to the tank Sunday afternoon. Would this cause the O2 depletion.

On your question about tank temperature, my concern is it feels to low!!, the thermometer says 26C so I guess thats OK.

Also, have you double-checked that your old filter is now compatible with the much larger tank? A larger tank might mean you need to upgrade to a more powerful filter - or even have two - one at each end of the tank.

Yes, as mentioned by someone else, make sure that your filter nozzle is sitting just at water level in order to create turbulance across the surface. If your filter isn't creating much turbulance then you can add an air stone. If you position the airstone flow so that the bubbles rising clash with the stream of water from the filter nozzle, this will cause extra turbulance and the air bubbles will be "bounced" around allowing more gases to escape from the tank water.

Athena

The filter that came with the tank was a fluval 350, this was the same as the filter I was using.
Would the filter supplied with the tank not be up to the job?

Thanks for the help.

 

[Miss Wiggle]

that's whats got your shrimp then

the active ingredient in white spot treatment can kill some sorts of fish and inverts, you need to do half doses if you have sensitive fish in the tank, you also need to increase aeration as something in the medication reduces the water's capacity to hold oxygen which explains the fish gasping.

Can you not adjust the filter so the outlet is somewhere else, it's very unusual to have it that low, it should be just below the water's surface really. If you can't do that you may want to look into getting a small powerhead or something like that to increase aeration (this will be much more effective that an air pump and stone which are largley decorative).

 

[nigsy]

Cheers for your quick replies,
Poor old shrimps.
The outlet pipe are on a fixed tube height, that comes through the base of the tank, I have pointed the directional heads to the surface though.
I need to do another dose of the white spot treatment on Wednesday, so before I panic about O2 levels I will just keep an eye on it and do small water changes daily until the medication has run its' course.
If the situation doest change a small power head will be the prefered answer.

 

[Miss Wiggle]

Oh I'm with you about the filter now, seen those ones.

You will need to do something short term to increase oxygen levels while treating (water changes won't work, that doesn't actually increase the oxygen in the water as some people think, the only way it increases aeration is if you pour water back in and break the surface of the water up), dunno how good you are at bodging/diy, but perhaps you can find a way to extend the outlet tube so it reaches higher up in the tank? If not then get a small powerhead asap, can pick them up from £5/10 from most fish shops, just stick it as close to teh surface as you can so you're getting waves.

 

[backtotropical]

Hi Nigsy and to TFF,

Miss Wiggle seems to be taking care of you, but i'd like to add one thing.

I need to do another dose of the white spot treatment on Wednesday, so before I panic about O2 levels I will just keep an eye on it and do small water changes daily until the medication has run its' course.

You mention doing water changes whilst medicating. This isn't a good idea as it will dilute the medication.

If you feel you must do water changes, you will need to part-dose the medication to bring the level back up after the water change. If you are unsure how to work out how much to use, i'll be happy to help you.

If the situation doest change a small power head will be the prefered answer.

I absolutely agree. A powerhead would do wonders in your tank just now, especially with you medicating for whitespot and having oxygen issues. I'd advise that you get one as soon as possible.

Cheers

BTT

 

[kj23502]

Hi nigsy

Just wanted to say to the forum. And it does look like your pretty well taken care of, huh!!! These guys/gals on here are pretty good

 

[nigsy]

Hi all,
Thanks for the quick responses/ advice.
Got a powerhead last night and installed immediatly and pleased to report all fish very happy this morning. Have turned it off for the moment as my 2 dwarf gouramis don't seem to keen on the current and went straight into hidding at the back of the tank, but they seem fine now the currents dropped.
2nd dose of white spot treatment goes in today, but no sign of infection spreading.

Quick question, I have never really had a problem with whitespot before, how long should I hold off doing a water change after the 2nd dose?

 

[Miss Wiggle]

glad you got the powerhead, won't need to be on 24/7 so you can give your DG's some respite. Set it on a timer or something for an hr or two a couple of times a day.

wait until you have finished the course of medication before you next do a water change.