Second Cycling? Please Help!!!

[FishyTT]

I finished cycling my 72g tank about 3 weeks ago (it took me 5 weeks using fishless cycling method). I added fishes in about two weeks ago. My fishes are:

* 11 platies,
* 8 corry cats
* 7 black phantom tetras.
* 8 octocinclus (sp?)

My tank also has lots of live plants.

The tank has been very stable for the last two weeks. Last Friday, I used the Vortex Diatom filter to fix the algae bloom (green water) problem in my tank. I left the filter run for 2 hours and the tank is now chrystal clear.

However, Saturday I tested my water and there're some Ammonia. The test result:

Ammonia - less than 0.3
Nitrite - 0
Nitrate - 10
Ph - 8.0

So, I'm really confuse now. Does my tank go through a second cycling?

I also have the following questions:

1. Does the Diatom filter somehow filter out the good bacteria?

2. In this situation, if I can find Bio-Spira and add it to my tank. Does it fix my problem?

I'm new to this hobby, please help.

Thank you very much in advance.

 

[Jericho]

Are you doing your weekly water changes? you should be doing 25-50% (depending who you ask) water changes every week. Your tank should be cycled, and with nitrates you have bacteria at work in there. The best I can say is that your fish are producing more amonia then your bacteria can handle, but if you have not changed your water in two weeks then it is not by much. If you keep up on the weekly water changes the extra bacteria needed will grow and you will be fine, But keep teating your water and change water as needed.

 

[FishyTT]

Yes, I'm doing 30% water change twice a week.

Also, I forgot an important factor. Last Wednesday, I added some salt to the tank to cure fin rot problem on 3 of my platies (I added 1tsp/gal total). However, I decided to set up a 10g hostipal tank later that day.

So, I did 40% water changes 2 days in a row (Thursday, Friday) to get rid of the salt.

Does overdoing water change get rid of the beneficial bacteria?

 

[sumthin fishy]

Your bacteria live mostly in your filter/substrate so extra water changes won't affect them very much.

Your bacteria colony will grow to the size needed. That means any time you add a fish your tank will "cycle". This is normal. Many people reffer to this as a "mini-cycle" since bacteria are already present, and they simple need to reproduce to match your biolaod. As jericho said, keep testing and change water as needed.

 

[iamgroovy]

Do you still have the same media in your regular filter? If you changed it that could be the problem. You only need to rinse it out in old tank water when you do your water changes. What kind of filter is it? Can you give us details about the rest of your equipment? During the week before you added the fish, were you still feeding the tank ammonia? If not, you may have had a die off there. Did you add all those fish all at once? Even though some say you can fully stock a tank after a fishless cycle, I stocked mine a few at a time. Yes, some of the bacteria may die off but I'd rather have too much than not enough. I'd just keep doing your water changes as much as necessary to keep the ammonia down and keep testing until you stabilize again. If you want to spend the $$ on bio spira, it would probably speed things up but I'm not sure. I thought it was mainly used to get things going and you're already going...

 

[FishyTT]

Thank you so much for your replies.

I have the Eheim Professional 2 filter. I have not touched the bio filter since I bought the filter. So, it has been in the Eheim for more than two months. Should I rinse it in the old tank water now?

After my tank cycled, I kept on adding ammonia every day to feed the bacteria until the day before I added the fishes. On that day I did a big water change (95%) to get rid of the extra nitrate.

I added my fishes in serveral phases. The first 7 platies on the first day. The rest of the platies and the corycats couple days later. I just added the tetras on Saturday. So, that's probably the problem. Because the ammonia appears a day after I added the tetras.