High Nitrites In Cycle

Otos need to wait until the tank has grown enough algae to feed them, and cories need a mature tank.

Ooops forgot about that 

I've got a pond too Manjr but we designed it just for wild life, it too is full of tadpoles atm

You added ammonia on 2 April to give a reading of 3 ppm. Stage 1.

You tested on 6 April and had ammonia 0 and nitrite 5+, and you added ammonia to give a reading of 3 ppm. That is, your ammonia was under 0.75 ppm and your nitrite over 2.0 - this is stage 6.

Stage 7 is test every 2 days. So test on 8 April and again on 10 April. I am expecting both of these to show zero ammonia with the way the first ammonia addition dropped, but if the 8th's test shows anything above zero, test again on 12th. You should be testing every 2 days and looking for 2 zero ammonias. So zeros on 8th and 10th, or 10th and 12th April. Or possibly 12th and 14th.
Once you get those two zeros, add a 1 ppm dose of ammonia and continue testing every 2 days, adding 1 ppm when you get to the second zero ammonia.
At the same time as testing ammonia, also test for nitrite. On the days you are due to add a 1 ppm dose of ammonia, if nitrite is over 1.0, add the ammonia. When you reach a day where nitrite is below 1.0, that is stage 10.
I'll not mention stage 10 yet, there is time for that later 


The reasoning behind having a minimum of 4 days between additions of the 1 ppm dose of ammonia is to stop the nitrite level getting so high it stalls the cycle. And that 4 days is only if you have zero ammonia on the second and fourth days after adding ammonia. If the ammonia readings are above zero, it will be 6 or even 8 days between doses.
It used to be thought that the ammonia eating bacteria would starve if they had no food, so other methods have you testing every day and adding ammonia every time ammonia drops to zero. And so much ammonia was added that nitrite went sky high and the cycle took forever.
It is now known that the bacteria don't starve, they can go several days without food. And even after a few weeks, they don't die but become dormant.
This is why on most sites you'll find the add-ammonia-every-time-it-drops-to-zero method, but I found the method I've written up on here on another forum and it seems to work.

We've all been in similar situations at some point, and the people here have given advice and seen us through.
 

Couldnt have done my cycling without the benefit of Sue's advice, the woman has the patience of a saint. 

Before you rush and do the big water change:
You need to add a 3ppm dose as soon as you have 2 days of double zeros 2 days apart. So double zeros on 10th, double zeros on 12th - add 3ppm ammonia on 12th and test on 13th. If you get double zeros again, do the big water change and get fish. The final stage is clearing a 3 ppm dose of ammonia in 24 hours.

You can get up 75% of the fish on your list as soon as the cycle finishes. This method of cycling grows enough bacteria to cope with the waste from more fish than 100% stocked, but I don't like to stock to the max, preferring to leave a bit of wiggle room should something not go quite right.
So yes, get your 12 cherry barbs. But don't leave it too long to get more fish or a lot of the bacteria you have just grown will become dormant due to lack of food. They will 'wake up' when there is more food (more fish) but the longer they are dormant, the longer they take to 'wake up'.

Just one word of caution. Some shops will sell you anything, others won't sell you more than a certain number of fish in one go. Arguing that you've just done a fishless cycle won't cut any ice - they have their instructions and they don't understand fishless cycling. If you get the latter type of shop, get 6 then go back next day for the other 6.

Thinking about it after I posted - if you don't intend stocking fully straight away, you won't need the full 3 ppm-worth of bacteria. You'll probably be fine with the amount of bacteria you do have.

Remember to check the ammonia and nitrite levels after getting each batch of fish - it is safe to get more when you've had double zeros for a week. If you do see a blip for either of them it won't last long, and water changes will keep the fish safe. Just delay the next batch of fish till the bacteria have caught up.

P@H is one shop that won't sell more than half a dozen fish at one go. Does that help 




That's the policy in my local one, no exceptions for people with 1000 litre tanks either.

I've heard tales from people who work at P@H. They are given a check list - no sale to anyone who refuses to tell them how big the tank is. I think most people will lie to get the fish they want.

I have to admit I hardly ever go in P@H these days as the nearest one sells very little variety of fish, and not the ones I want.

Ironic they only let you have 6 fish at a time when they're perfectly happy to sell you fish and tank at the same time.

That said, I nearly got hugged by one P@H shop assistant fish specialist when I told her I'd cycled all my tanks with a fishless cycle. She was genuinely delighted.

One burk working in MA in St Albans once told me you could keep a betta in a really small tank and not worry about the water quality too much as they live in puddles in the wild.  No wonder people get given bad advice sometimes.