Fishless Cycle

[Jon Bennett]

Hi All,

Currently part way through my fishless cycle.

I am having to add around 3ppm of ammonia every 24 hours because the bacteria is loving it!!

My nitrite & nitrate levels are off the chart and my pH is around 8/8.2

Would you suggest doing a 50% water change to try and get the levels of nitrites & nitrates readable? Or should I just leave it??

Thanks in advance,

Jon

 

[Baker]

I recommend stopping the ammonia, letting the spikes dissipate and then changing out the water to remove nitrates

 

[Jon Bennett]

But surely stopping the ammonia would starve the bacteria?

 

[Essjay]

No, the bacteria can go weeks without food. They will become dormant first. The problem with adding too much ammonia is that the nitrite level will get so high it will inhibit the growth of the nitrite eaters and stall the cycle.

You could get away with partially emptying the tank but if you have added a lot of ammonia you could need to empty most of the water to get a nitrite reading on the scale. It might be better to just empty the whole tank.

Then follow this method http://www.fishforums.net/threads/cycling-your-new-fresh-water-tank-read-this-first.421488/ adding ammonia only when it tells you to. But because you have already grown a lot of bacteria, after the addition of 3 ppm ammonia I would test every day rather than every third day.

 

[Jon Bennett]

That's interesting, I have never read that method of fishless cycling (in regards to the amount of ammonia to add) most say to keep dosing ammonia levels to the level you started with.

 

[Essjay]

The chap who wrote it did so based on new evidence about the bacteria. His method is based on the fact that the bacteria don't starve in less than 24 hours as used to be thought, and this allows the addition of ammonia to be kept low enough to stop nitrite ever getting above ~15 ppm, the point at which the growth of the nitrite eaters becomes inhibited.

 

[eaglesaquarium]

That's interesting, I have never read that method of fishless cycling (in regards to the amount of ammonia to add) most say to keep dosing ammonia levels to the level you started with.

That was the belief for a long time. It turns out that the bacteria need far less than we believed even a few years ago. The science of the hobby keeps updating!!!

So... with that said, I'd recommend you immediately complete a large water change to deal with the nitrite that you have in the tank. If your system hasn't crashed yet, it likely will soon.

Change a large amount of water up to the full tank... and then do the full dose and test everything in 24 hours. You might be very surprised to see that the nitrite won't be that high at all, even with the ammonia being gone.

1 ppm ammonia will convert to ~2.7 ppm nitrite.

So, 3 ppm ammonia will convert to ~8ppm (which would be 'off the chart')... but my guess is that after 24 hours, you will see the ammonia sitting at 0, but the nitrite will likely be about 4 or so, if not lower.

When the nitrite falls below 2ppm... add a 'snack' dose (1/3 of your 3ppm dose amount)... and continue to add a snack dose ever 3-4 days, until the nitrite falls to 0 ppm.

Then add the 3ppm and test after 24 hours. From that point, you add 3ppm only when you get double zeros. And when you get double zeros for both in ammonia and nitrite in 24 hours or less... you are cycled!!!