Cycled Now?

Freshwater Noob

AC Members
Dec 8, 2007
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My 40 gallon has been cycling for over a month and a half using fish flakes (for some reason no one has the ammonia with no surfacants around here). I left for a week for vacation and I came back to the following readings (I bought a master freshwater test kit over the holidays using the advice of the board)

pH - 7.4
Ammonia -0ppm
Nitrites - <.5ppm
Nitrates - 40ppm

Am I cycled? I am going to do a 25% water change if it is ready and go get some peppered corys to start. Are the peppered corys hardy enough to put in first?
 
pH - 7.4
Ammonia -0ppm
Nitrites - <.5ppm
Nitrates - 40ppm

Am I cycled?

Is 5ppm the least concentration of nitrites which your test kit will measure?

If not then "no: I would not induce fish" but would continue adding fish flakes (about 1/4 teaspoon/day") until your nitrites are 0 or "whatever the minimum concentration which your test kit can observe".

Your post indicates to me that you are on the "down leg" of the nitrite cycle but I do not understand the 1.5 month duration necessary to cycle your tank.

"Are you sure" that you have plenty of biological and mechanical filtration media for your 40G tank and that the turnover rate of the water in the tank through the media is 10 times/hour?

TR
 
I have a filter for a 60 gallon tank on my 40 so that I would have plenty of filtration. Not sure how to calculate the 10 times/hour but I thought that a little overkill on the filtration would save me some trouble later. Also, the reason for the month and a half was because I didn't want to add fish to my newly established tank and then leave them to themselves for a week. Also, there were a number of mistakes I made early on in which I had to drain my tank completely and do a partial water change (tried to manipulate my ph and then I read some of the posts on here so I got rid of the water that was full of chemicals). My test kit can measure down to 0 nitrites so there are some residual nitrites in the tank. I didn't have a master test kit until now so I have not been able to monitor the nitrite to nitrate conversion like I wanted but now I can ensure that the tank is ready and safe for the fish before adding.

So should I just wait it out and keep adding flakes until nitrates are zero?
 
The reading he posted for nitrites was .5ppm not 5ppm ...So you are not quite there yet...keep adding flakes for now...when ammonia and nitrites both get to 0ppm and stay there for a few days then you do your large water change to get the nitrates down to around 20 or under before adding fish/
 
Ammo and nitrites should always be at 0 for a cycled tank. Your very close to the finish though.
 
I say do a 90% water change and add fish.
 
:iagree: Once you have your ammonia and nitrites down that far you know that your bacteria level is adequate for a couple of small fish. Just add in the fish slow (only a couple at first) and then test your water daily.

"Are you sure" that you have plenty of biological and mechanical filtration media for your 40G tank and that the turnover rate of the water in the tank through the media is 10 times/hour?

10 times per hour is a little excessive. The need for filtration is dependent on the species of fish, the bioload, the substrate, and the plants. If you are running a bare bottom, unplanted tank with a very heavy bioload you may need 10x per hour. However, if you have a heavily planted, lightly stocked tank, you may be able to get away with 2x or 3x per hour if you even need a filter at all. With enough plants, a bubble wand might be all that you need.
 
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