Backyard Aquaponics
A place to discuss aquaponics

Hi, everyone!!

We recently bought 100 trout fingerlings as that was the minimum amount we could buy.
Half went into a 1000L tank with 1000L of growbeds- System 1. System 1 has been running for about 8 months, so no issues with that one.

System 2 is identical, but uncycled: 1000LFT, 1000LGB. It has had the 50 trout larger-than-fingerling for four weeks.
A week ago (week 3), ammonia spiked to between 1-2ppm
Nitrites soon followed and have been off the chart for days. I have been doing small water changes (10%)and a few big ones (40%).
Today (week 4), the results were:
ammonia- .25ppm
nitrites- off the chart
nitrates- between 5 and 10ppm

We had our first dead trout this morning- the littlest one. I did a 60% water change (with creek water). I also added more air bubblers.

Should I:

- add salt 1ppt asap?
- move the trout to System 1 until the nitrites fall?
- do another water change tomorrow?

I don't want to add salt and then do a water change and dilute the salt.
Clearly, cycling is occuring, but the goal now is to minimise fish deaths.

What would be my best courses of action?

Thanks so much.

Here is a link to my System thread:
http://www.backyardaquaponics.com/forum/viewtopic.php?f=18&t=12019

Hope that works, haven't done it before.

Add salt (probably 2-3ppt) and perhaps put some of the water from your established system in your new system to give it a helping hand.

Within reason, consider adding some of the cycled system water into the un-cycled system, then topping up the cycled system with your clean water.

If the cycled system has a filter in it, add the filter material to the new system to promote bacterial colonisation in the new system. (There's more bacterial in filter gunk, than in water).

Salt up to 3ppt and maintain that level by salting any water to be added to the system.

Aerate and pump, continuously.

{Arbe beat me to it}

If you are using creek water you dont have to worry about chlorine.

I would do a massive water change, probably around 90%.
Remember, if your water is off the scale, nitrites are about 10ppm or more.
Doing a 60% water change will drop to 4ppm, which is still very high.
Once you have done your water change, then add salt. 6ppt will be good for the fish, and after a later 50% water change you will still have 3ppt.

I would move some fish to the cycled system as well. Not too many, you may cause a spike in that system too.

Water changing will only delay the cycling process... and an ammonia reading of 0.25 isn't a problem...

Just salt to 1-2 ppt... to mitigate against the nitrites... hopefully it's not too late.... it may be for some...

What's your pH & temperature... and the pH of your source water....??

Water changing might actually be the worst thing you could do....

and dont feed till nitrites back right off

Nitrites are off the scale!
Whats the forecast in Tas for the next week? ~16 degrees???
The bacteria is going to take atleast a week to build up any numbers to make a difference.
The fish are all going to be dead by the time the cycling is finished.
And you are going to get nitrobacter build up on 2-3ppt of nitrites at the same speed they will build up at 10ppt.

I struggle to see how a water change is the worst thing you can do.
Nitrites off the scale is deadly!

But like I said in my post, that is what I would do.
Obviously there is more than one way to skin a cat...

Although I think doing water changes is the dumbest thing you can do for nitrites, the fish were introduced before the system had cycled. I would tend to agree with Werdna on this one, its creek water I assume with bacteria in it already.

Yep.. and have been for a few days... even reducing them by a water change.. will still leave the fish at risk to further nitrite toxicity....

You need to salt to mitigate against the nitrite toxicity... regardless of your reading...


They wont.. from ammonia... but might from nitrite poisoning... if you don't salt...


Yes...

The "nitrobacter"... will only process the nitrites... once the ammonia level drops to zero, or near to it... as is happening...

The nitrobacteria processing is related to temperature.... but the level of nitrites makes no difference... other than the ultimate corresponding level of nitrates produced...


Changing water would dilute the nitrites.. sure... but they'd still be there at some level.... and still toxic to fish... unless you salt.... !!!!!

As to why water changing is not a good idea..

1)... it can delay the cycling process...

2)... while the current level of ammonia is low.. and I note your water is 16.. and unlikely to be toxic... ammonia toxicity is related to temperature and pH...

It's possible that if your system has a pH < 7.0.... at a certain temperature.. and ammonia reading.... to be "safe"....

But you can end up "unsafe"... if you change the water to a pH > 7... with the same ammonia reading... and temperature...



For instance...consider...

At 20 degrees.. and a pH of 7.0... ammonia would be safe to a level of around 5.... change out the water to a source water of pH 8.0... at the same 20 degrees... and your toxicity is then only 0.5....

Changing can.. (and I said it could be).... be the worst thing to do...

Not because of nitrite poisoning.... (salt will fix that)... but ammonia poisoning...

Not a good thing if fish are already stressed from nitrite exposure...

If you're "fishless cycling"... water changes are just completely unnecessary... and detremental...

If you're cycling with fish... then you should only be feeding very lightly, or not at all...

And shouldn't be seeing ammonia readings higher than 1-2... unless you're grossly overstocked... which will ultimately only give you a nitrite reading of 0.5 - 1...

You certainly shouldn't be seeing ammonia readings of 8-10... which is what you'd have seen.. to get a nitrite reading of 5+....

So yes... in that circumstance... a water change would probably have been reasonable... at the ammonia stage...

The nitrite stage only requires salt....

Mind you... the nitrite toxicity... might be nobbling your fish.. if your ammonia was 8+ previously anyway... regardless...

A properly managed cycling process just doesn't need water changes...

Rup, I am not going to keep arguing with you.
I know you will fight your point to the death, and neither of us are going to change their opinion.

I know that the average ph of water in Tasmanians streams is low, around the 6-6.5 mark.

Nitrite poisoning can me more deadly to fish than ammonia.
It causes brown blood disease, which stops the bloods ability of carrying oxygen.
That, preceded by burning to the gills by ammonia, can mean that whatever your DO, the fish can easily still suffocate.
Nitrite poisoning can kill fish weeks after the spike, which is why it is common for people to not have any water problems and fish turning belly up.

I agree with your point about properly managed cycling not needing water changes, but IN MY OPINION this is not a properly managed cycle (No offence Blythe).
IN MY OPINION, ammonia and nitrites should never go off the scale.
It is easily controlled by feeding.

The water is coming from a stream, there will be good bacteria in the water.
IN MY OPINION Blythe should use the natural resources around them. If it was tap water being used my answer would have been different.

No arguement, or dispute there what so ever Werdna...

And the damage may already be done in this case.... water changes wont alter those that may already be effected... but salting will save the rest...


Again.. no argument there at all Werdna... complete agreement..


No arguement either that stream water may include some beneficial bacteria.... but it could also include parasites and other pathogens... that may set up a secondary infection in already stressed and weakened fish...

But the point I'm making.. is that water changes... at this stage... near cycled... aren't going to benefit anything really... salting will... the rest is a matter of patience...

I guess we can agree with 90% of what the other is saying then

Personally Id run the systems together till it sorts itself out by pumping the new system through the old and then back into the new.. basically combining them.

I did this early last year when I had 2 systems sitting side by side and I had a massive amm spike in one due to my 3 year old dumping 2 kg of feed in which went un noticed for 8 hours.

By running one through the other and back again everything was diluted... and in this case the mature system would eat up those nitrites and assist in getting it back into check.

Others might say you could further the nitrite poisoning but if you salt as Rupe has mentioned I think you could sort this out real quick.

Just my opinion.

Hmm...not sure i I should tell you all what action I'm taking. This is getting heated!!

OK, I admit it. I fed the fish.

But they seemed so HUNGRY! I'm a mother, I couldn't help it. And I thought I was feeding minimally...sort of...

So my nurturing tendencies may result in their deaths, how awful. (Believe it or not, my own children are very slender!).

That said, I never saw the ammonia higher than 2ppm, and I tested everyday, maybe missing one. I don't really understand how the nitrites got so high if ammonia needed to be 8+ to get that way because it never got that high (unless it spiked and dropped 6ppm within 24 hours...)

Anyway, I really appreciate all the advice (even if it is conflicting ho ho). I have added 1-2ppt of salt and I will test tomorrow morning, check for deaths, and decide on any further action. I like Charlie's idea of combining the systems, but I also don't want to mess with something that isn't broken! I'll decide tomorrow.

If the fish survive, I will let you know. If I never write again, they died and I'm too ashamed to show my face round these here parts.


Only kidding, I'll let you know either way!