Fishless cycle using food & established media

Ophitoxaemia

I am doing a fishless cycle right now (day 11) using only fish food and media from an established tank. Right on track so far.

Some time ago someone said to think of feeding the tank and not so much the fish. Now that I'm fishless cycling, that makes a lot more sense to me: whether the fish create ammonia or the fish food decays into ammonia, we are really feeding the bacteria in the tank, and the fish and plants also just happen to live there.

Water is still crystal clear. It seems the bacteria will eat all the fish food as long as there isn't too much.
 

CindiL

I am doing a fishless cycle right now (day 11) using only fish food and media from an established tank. Right on track so far.

If you're using an established filter you shouldn't need to fishless cycle unless you're planning on heavily stocking this new tank? (more than the old tank). The media should give you an instant cycle.
 

Ophitoxaemia

CindiL My ammonia peaked at 2ppm on day 3 and went to 0pmm on day 8, but the nitrite is still at 5ppm. Perhaps I didn't transfer over enough media at the start?
 

Dunk2

CindiL My ammonia peaked at 2ppm on day 3 and went to 0pmm on day 8, but the nitrite is still at 5ppm. Perhaps I didn't transfer over enough media at the start?
Sounds like the media you transferred definitely gave the cycle on your new tank a jump start, but not an instant cycle.

And yes, you likely didn’t transfer enough media or there wasn’t a high enough bioload in the cycled tank to fully process the ammonia.

Whatever the case, good for you for continuing to test before adding fish. This is an example of why I suggest that folks not assume an instant cycle when they use media from a cycled tank.
 

MrMuggles

Water is still crystal clear. It seems the bacteria will eat all the fish food as long as there isn't too much.
The clarity comes primarily from your mechanical filtration, the bacterial colony will have a small impact on clarity but it’s really minor compared to the mass of particulates filtered mechanically.
 

Azedenkae

Some time ago someone said to think of feeding the tank and not so much the fish. Now that I'm fishless cycling, that makes a lot more sense to me: whether the fish create ammonia or the fish food decays into ammonia, we are really feeding the bacteria in the tank, and the fish and plants also just happen to live there.
In theory this kinda does, in practice feeding the tank makes no sense.

(Freshwater) fish create ammonia directly (and some urea), so rather if you dose ammonia you are replicating what fish produces more accurately than letting fish food decompose anyways. Unless you'd think the majority of fish food added to a tank decomposes, rather than is consumed. But that's not the important part of this.

Cycling is about establishing autotrophic nitrifiers, and unfortunately fish food or any other organic compound is unavailable to these microorganisms as a carbon source. Rather, the majority of the fish food would likely be consumed by non-nitrifying microorganisms as both a nitrogen and carbon source (along with other elements), promoting their rapid growth.

This is seen as a decline in ammonia, yes, but unfortunately does little to help with the cycling process as the nitrifiers are outcompeted. However, if only pure ammonia is available, then the non-nitrifiers cannot really grow and thus allow the autotrophic nitrifiers to grow in place.

It is a slower process, but of course the only real way to ensure autotrophic nitrifiers are growing, and thus a robust nitrification capacity in the future.
 

Ophitoxaemia

Azedenkae
"Cycling is about establishing autotrophic nitrifiers, and unfortunately fish food or any other organic compound is unavailable to these microorganisms as a carbon source."

What is their food source? Where do these microorganisms come from?
 

Azedenkae

What is their food source?
Carbon dioxide and water. Kinda like plants. They do need to obtain elements like nitrogen, phosphorous, and sulfur from other sources, luckily readily available in the environment for the most part.
Where do these microorganisms come from?
Survivors in tap water, air, established biomedia, carried by plants or fish, bottled bac products, and probably other sources too.
 

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