Is my fishless cycle done?

[artgalnj]

Hello,

I'm new to the forum, but I've been lurking around here for quite some time. I've been in the hobby for 3 years now and I just started my second tank. I have a question regarding fishless cycle and I can't seem to get a solid answer. The new tank is planted w/ various sword and crypt plants. I added filter floss from my established 20 gallon into the filter of the new tank. Each morning I add ammonia to bump up the ammonia level and within 12 hours my ammonia level drops to 0, but I still show low levels of nitrite at the 12 hour mark. By the next morning however the nitrite level is back to 0 (it has been this way for 4 days now). Does nitrite need to drop in 12 hours for a fishless cycle to be considered complete or is 24 hours ok? Also, I'm reading VERY low nitrate levels (5.0 ppm). I think it's due to the plants that I have. Is that a sensible conclusion? Thank you in advance for your help.

[gzeiger]

You should be fine. The answer to whether 24 hours is fine really sort of depends on how much ammonia you added, but once you're seeing a consistent reduction like that you should be ready to add fish.

I recommend not worrying too much about these fine details at the end, because Nitrobacter bacteria under optimal growth conditions will double their population about every 13 hours, so even if you're not quite there you're close enough that they will catch up effectively instantly.

[artgalnj]

Thank you kindly for your response! I've been giving it a decent shot of ammonia everyday, bringing the ammonia up to 3 ppm (perhaps even a tad higher than that). Today I didn't dose as much ammonia, so I'll see if I drop in 12 hours. But I had a feeling I was okay. Once I added filter media from my old tank into this one, the cycle took off.

Thank you again!

[gzeiger]

A normal stock of fish won't come anywhere near producing 3 ppm ammonia in one day, so your filter is probably well past where it needs to be to support whatever you plan to put in the tank.

Next time, there are easier ways to do this when you already have established tanks

[artgalnj]

Originally Posted by gzeiger

Next time, there are easier ways to do this when you already have established tanks

Yeah, I realized this. Originally, I didn't want to use anything from my 20 gallon, because I have snails in the 20g and I didn't want to transfer them into the 75g. Didn't matter anyway because with all of the plants in the new tank, the snails appeared and they seem to have withstood the daily bombing of ammonia. The plants are thriving though! I've never had luck with live plants, so this is a first. Now I'm thinking of converting the 20g into a high tech planted tank...just what my husband wants to hear .

One more quick question. Being that nitrates are so low (ranging from 0 to 5 ppm), should I still do a water change? I've read that one should do a water change at the ending of fishless cycling to lower the nitrates, but they're very low already. Thank you again for the advice. Take care!

[gzeiger]

The fish will be fine if you skip the water change. Lots of people have more than 5 ppm nitrate in their tap water. The plants may appreciate it though. There are lots of unexpected micronutrients that may be depleted from the water now. It probably doesn't matter very much though.