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Tank Crash!


Chi

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Hey all, just a quick rundown on my display tanks situation so that I may gather some ideas/solutions.

The tank is a 48X14X20 (225l?) and was setup roughly 8 weeks ago.

The tank was setup and cycled over a fortnight period and slowly stocked with Juvies (3-5cm). The stocking proceeded with about 2 fish every 4 or so days. Everything seemed fine. As per continuous testing and regular water changes, the tank by all reports was cycled. The tank had about 16 fish by end. The tank has a total turnover of maybe 2000 lp/h (2 X AC70, Eheim 2213, 2X A1 Internals + a Sponge filter) as it is heavily overfiltered. The substrate was pool filter sand.

2 weeks ago I was given a large quantity of coral sand mixed with shell grit from an ex-reef tank. I proceeded to wash this EXTREMELY thoroughly over the course of 3 days. I intended to switch the subtrates as I had nothing buffering the water and thought switching the sands would save me long-term headache.

So I proceeded to gravel vac the old sand out and replaced it cup by cup, about 10kg of it (I prefer my substrates just covering the bottom).

Since then the tank seems to have crashed and I have lost almost all fish one by one.

Symptoms are heavy 'gasping' but no moving to the surface (probs not flukes) and only after 10 or so fish passed have some contracted whitespot and as such I doubt this is the initial cause of death. The fish added latest seem to have coped best (4 loaches).

Temp used to be maintained at a stable 25C but I have increased that now to 28C and treated with Protozin (removed carbon/purigen) to fight the white spot. There are about 4-5 fish left.

My guesses are:

- Replacing the gravel relatively early has restarted the cycling process (I thought there would be enough bacteria in the filters to cope).

- Residual salt has burnt the fishes gills (But I washed thoroughly and if anything thought a little salt would be beneficial?)

Anyone have any ideas?

I have tested the water many times and everything reads fine, Ammonia 0-0.1, Nitrite 0-0.1 and Nitrate negligible. These were tested over several kits including in-LFS tests. I have been keeping up with normal water-changes. Ph before gravel change was 7.4, it now sits at about 7.6.

Anymore info needed?

Thanks all in advance for the help!

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Sounds like ammonia and nitrite posioning... how can you be sure your tank was cycled?

did your store tell you add cycle or nitrovec and then say you would be ok after this? <_<

sounds like your tank wasnt properly cycled and then spiked with incresed bio load <_<

As for the whitespot..... did you get the fish from the same store? <_<

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Sounds like ammonia and nitrite posioning... how can you be sure your tank was cycled?

did your store tell you add cycle or nitrovec and then say you would be ok after this? <_<

sounds like your tank wasnt properly cycled and then spiked with incresed bio load <_<

I'm sure it was cycled because testing ran concurrent with a cycle up until jumping nitrate/big water change then a slow addition of fish.

Stores didn't offer much advice as you can see the situation is quite complex due to the fact that all tests over the month period show little or no Ammonia/Nitrite.

As for the fish, all were bought from breeders off this forum (and they were great fish!) with the exeception of the loaches.

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So you had big nitrates nitrite = 0 and ammonia = 0?

If so, maybe a pH swing or a too large a water change wiped out some of your bacteria or there was not sufficent barcteria to support the current bio load in the first place.

Maybe some fish died from whitespot and the ammonia and nitrite spiked because of that - too many dead fish and not enough good bacteria to cover it?

If your tank was properly cycled the ammonia and nitrite should return to 0 soon upon the removal of any dead fish

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Not sure how long you went before fish started to die, but just so you know, to cycle a tank you could be looking at 4-6 weeks (if not longer). If deaths occurred inside this time frame, I’d still be looking at ammonia/nitrite issue (regardless of what you say about your test kit results).

My other thought was what water ager did you use.

Fish don’t die without a reason, and I expect it is something you have overlooked, or possibly don’t understand -though you sound like you’ve got the right knowledge.

The substrate from the marine tank can’t have been the issue by the way. However, you may have moved a significant amount of bacteria, which may have only just being keeping up with the bioload (you don’t say what sort of biological media in filter, though sponges should have had a good surface area).

White spot will be a secondary issue.

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Not sure how long you went before fish started to die, but just so you know, to cycle a tank you could be looking at 4-6 weeks (if not longer). If deaths occurred inside this time frame, I’d still be looking at ammonia/nitrite issue (regardless of what you say about your test kit results).

My other thought was what water ager did you use.

Fish don’t die without a reason, and I expect it is something you have overlooked, or possibly don’t understand -though you sound like you’ve got the right knowledge.

The substrate from the marine tank can’t have been the issue by the way. However, you may have moved a significant amount of bacteria, which may have only just being keeping up with the bioload (you don’t say what sort of biological media in filter, though sponges should have had a good surface area).

White spot will be a secondary issue.

HI,i would definatly agree with cthomsons diagnose,particully the water ager.

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While your filter may? have cycled effectively, when you add in a large quantity of new substrate you will go through another "new tank syndrome" cycle since the new substrate has to colonize too. This is exactly what your new filter media did remember. Even if your filter is already seeded, it just cant keep up and large amounts of "new" substrate with colonising nitrosomas and nitrobacter can create large spikes in ammonia and nitrite. Luckily the mini cycle period will be much faster since there is a lot of benificial bacteria already present.

Sounds like your ammonia and nitrite is under control now though. Gill burns are probably ammonia not salt.

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Thanks for all the help guys. I will just have to start restocking :(

Whitespot has cleared up and I am on 3rd day of treatment which is a good thing. I will continue to treat today and on day 6 to be sure but!

The water conditioner I use is Prime. However as of late I notice opening the bottle has developed an 'egg' smell. Does Prime go off? I will probably search online...

The biomedia is the usual that comes in ACs and Eheim Cannisters, mix of noodles and foam. But yeah have a big sponge running in there too...

Funnily enough the survivors are the fish that are probably least hardy AND most susceptible to ich...the clown loaches!

How long do you think I should wait before restocking? 2 weeks with big water changes?

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The water conditioner I use is Prime. However as of late I notice opening the bottle has developed an 'egg' smell. Does Prime go off? I will probably search online...

I dont know about going off, but i would doubt it. (unless we are talking about 5 - 10 years).

That sulfery/egg smell is normal. Lovely isnt it.

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How long do you think I should wait before restocking? 2 weeks with big water changes?

Great posts, lots of learning for noobs like me.

Noob question.

Is there a difference in the bacteria which grows in salt and fresh water?

IMHO you might add new fish more slowly, with less reliance on the Prime and more on the Time...

What new fish this time around?

Old Dave

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