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Cycling: Input appreciated

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Day 15 of my fishless cycle, and my tank had turned into a swamp. The water is approaching opaque, and my frogbit is getting fried. There is a brown film on the glass, filter, and heater. Ammonia is still pretty high. Is this something I should let run it’s course, or should I clean it and start the cycle over? I’ve never had a tank look like this while cycling. Any input/advice is appreciated. This is going to be my bettas new home when it’s ready.  





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Posted (edited)

Ok, let’s clear up some things…

First, what is your source of ammonia for the attempted fish-less cycle?

Second, what is the actual ammonia reading, and what method are you using to measure it.

The dark stained water is from tannins being contributed by the piece of wood, did you boil it before placement?  In any case, this will not affect the cycling, or lack there of.

As for the frogbit, it’s not “getting fried”, but is showing signs of potassium deficiency, very common.


Edited by tonyjuliano
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@SarahO The brown film could just be diatom algae which is common for new tanks and should stop happening after a while (something to do with them running out of silicates?).

The brown water is just tannins like other people said. Some people like this look (I do!) and do it intentionally as it replicates the natural environment of some fish so it's definitely not harmful but once your tank is cycled water changes will remove it. 

Ammonia at 1.0 ppm isn't that high for a fishless cycle, in fact most people recommend dosing around 2 or 3 ppm, but I doubt it matters that much as long as it's not ridiculously high. I would advise just to let it run its course and keep testing and not to clean anything. As the ammonia starts to drop and you see nitrites instead keep topping up the ammonia just a little, the nitrites will build up for a while but eventually they will start to drop and you will see the nitrates increase instead.

In my recent experience it took ages for the nitrites to start processing into nitrates but then when they did it all went very quickly. 

Most people will say once your tank can process 2 ppm of ammonia fully into nitrites and then into nitrates all within 24 hours it's ready for fish. Personally I think that's a bit of an arbitrary number and depends on how many fish you plan on adding etc, if you are sensible and add fish gradually I doubt a singly guppy for instance is going to produce enough waste to get anywhere near 2 ppm ammonia in 24 hours. 

Just make sure there is no ammonia or nitrites left in the water when you add your first fish and it will be fine. (You can do water changes after to remove the nitrates but make sure the tank itself has dealt with the ammonia and nitrites). 

What fish are you planning to keep?? 



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@SarahO I assume that the tank the betta and corydoras are in is cycled. If so, you can grab some of the filter media from that aquarium and add it to this aquarium you are attempting to cycle. This will help speed the process up greatly. 

If you do this and it does cycle the aquarium, you can do a 50 percent water change to clear up the water a bit. The tannins are just coming from the wood. You could even use activated carbon to clear that up if you would like. 

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On 7/6/2021 at 11:06 PM, SarahO said:

ammonia is 1.0 ppm and nitrites are 0.25 ppm.

Judging by this I would say you are in the beginning stages of the cycle.  I would bet that Nitrates would test zero at this point.  Just need to let it go…do not do any water changes!  Since you have nitrites shows that it is moving along!

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