Empty and Cycled 125 Gallon Tank
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Empty and Cycled 125 Gallon Tank

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Empty and Cycled 125 Gallon Tank
Old 12-18-2013, 06:13 PM   #1
Empty and Cycled 125 Gallon Tank

I have an empty 125 gallon tank that is completely cycled. I used pure ammonia (Dr. Tim's overpriced ammonia - no ACE store near me) to cycle it. If I bring the ammonia up to 2.0 ppm, in approximately 12 hours, it is back to 0.0. Nitrite has been 0.0 for 3 days now after a large spike. Nitrates are between 40 and 80 ppm (I cannot discern the different color reds used on the API chart.

I want to stock the tank on Saturday after a 90% water change. I only want peaceful fish, like Tetras, Platys, Danios, and Cory fish. The water comes out of my tap at 7.8 PH, 6 KH, and 9 GH. My TDS meter reads about 150.

I have an RO/DI filter unit and I have been toying at the idea of doing a 50/50 mix to lower the KH to the 3 range (and maybe pull the PH down a bit too.) Once the initial fill up is done, I think a 15% water change weekly is doable with an RO/DI mix.

I have a 29 gallon with 3 Mollys, 3 Columbian Tetras, and 2 Corys. I started out with 7 Tetras 10 days ago, but I think one of the 3 left is a murderer and has killed 4 of them. I want to remove them and the Corys and transfer them to the 125 gallon and turn the 29 gallon brackish for the Mollys (I will get more.) I do not want more Columbian Tetras as I have read that they can be aggressive and I am tiring of finding dead fish in my tank every other day.

So I have 5 fish to add to the 125 gallon tank on Saturday. My question is, how many more should I add at once to keep the bacteria colony that I have alive (or mostly alive.) I was hoping that maybe I could get away with 3 more Cory fish, 7 or so Platys, and maybe 6 or so Guppies. Will that be enough?

Sorry for the long post, just wanted to provide some background info. Thank you so much.
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Old 12-19-2013, 09:27 AM   #2
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welcome to the forum

Providing information is never something for which to apologize!

A peaceful community tank in a 125.....your options are almost limitless.

You don't have to be concerned about keeping the bacteria alive. The bacteria colony is not static - there is an ebb and flow based on conditions. Yes, if you only add the fish you have now, the bacteria colony will eventually die back to a size proportional to the bioload. And when you add fish, it will grow to meet the need.

You can add all your fish to the tank at once, but i would absolutely not go and add a whole bunch of new fish to the tank as well. In a tank that big, with what you want to stock, you could easily put 100 fish in there. Because of the tanks capacity to hold fish, I STRONGLY suggest quarantining new fish. We it me, I would use the 29 for quarantine. In the 29, you'll be able to quarantine large schools of fish rather than be forced to build your schools in small groups. Too, if you want to do a brackish tank for the mollies, I would suggest a larger tank. They aren't small fish, and they multiply. Plus, you will probably want to add a few others - archer fish are one that I've always wanted to get. And dragon gobys. I would look for a 55, or at the very least a 3 foot long tank (30 long, 45, etc.) for just the mollies. Too, I would pick up at least a 10, preferably a 20 to be your brackish quarantine tank.
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Old 12-19-2013, 04:36 PM   #3
Thank you for the advice. I actually have an empty 55 gallon that I bought a few years ago and never set up. I need a stand and cover and lights ... etc. etc. My goal was to eventually tun that into the brackish tank and convert the 29 gallon to the hospital tank. Thank you for confirming that as the prudent thing to do.

I was going to place an order with Liveaquaria for the first batch of fish ... since the tank is empty and these would be the 1st fish in, I did not see a point in quarantining them. Am I wrong on this?

I was going to order about 50 fish (small ones) to start and then just leave it alone for a good while. I would rather be understocked for a while to make sure there are no problems.
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Old 12-19-2013, 10:12 PM   #4
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Yes, the first fish in the tank will essentially be quarantined in the show tank. I think it would be a good idea to start with 2 largish schools for your initial stock. 10-15 fish each. I would then use the 29 gallon to move fish that show any kind of problems. One of the concerns of adding lots of fish at once is the threat of the spread of disease - some of which usually require you to treat the whole tank, which in your case could be hugely expensive. Separating any suspicious fish is important for protecting the rest, in your situation, in my opinion. I think adding 50 fish at once is risky and exposes you to potentially huge problems. I've seen peoples accounts of doing so and many had a hard time of it. The more fish you add at once, the less control you have. There isn't anything good that can come from stocking your tank too quickly - only bad things.

I quarantine new fish for at least a month so it would take me well over a year to fully stock such a tank. I'm sure others would finish faster, especially those that don't quarantine. Quarantining is extremely important for long term success in the hobby. It;s the only thing I really take seriously.
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