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wetrelief 11-07-2012 06:18 AM

when to add fish?
I started a walstad method 40g breeder tank this past friday. I used MCOP and black diamond for my cap. The main question I have is when do you add your fish? I know some add fish right away, but I was warned with MCOP I will have a ammonia swing as the soil decomposes. Should I wait until after the swing...and also is it better to do water changes during that period or to let the tank stable itself?

somewhatshocked 11-07-2012 12:06 PM

You don't add fish until your tank has completed the initial cycle. When ammonia and nitrite are at zero.

You'll have to make sure you're providing an ammonia source for the bacteria to grow during that time.

wetrelief 11-07-2012 03:54 PM

Thank You. Is household ammonia a good source? Also what would be the dosage rate for a 40g tank?

dougolasjr 11-07-2012 04:57 PM

You really want an Ammonia without any surfactants. Not sure on the dosage.

wetrelief 11-07-2012 05:29 PM


dougolasjr 11-07-2012 05:37 PM


Originally Posted by wetrelief (Post 2070511)

Check out the link below.

Matt1977 11-07-2012 08:31 PM

Your substrate should have enough ammonia to start the cycle. Even potting mix has ammonia in it. You have to make sure you have a bit of circulation in the tank so that the bacteria colonies have O2 to survive and multiply. I say keep an eye on your ammonia levels...

Green_Flash 11-07-2012 09:54 PM

usually 4-6 weeks

discuspaul 11-07-2012 10:01 PM

As dougolas said, make sure the ammonia you have, has no surfactants or any other additives. It will likely be a 10% ammonia solution with water.

Test your water to see if your substrate has leached any ammonia - if so, and you have a reading of between 2 and 4 ppms, that should be good to get things started.

Test every couple of days, and should it test out at 1 ppm or less, then add some ammonia - try 2 or 3 teaspoons of the 10% ammonia solution which should be good for your 40 gal to test out @ around 3-4 ppms. Keep adding a couple of tspns of ammonia every time the test shows the ammonia level in the tank has dropped to 1 ppm.

It will very likely take from 4 to 6 weeks to go through the entire cycle, during which nitrites will have peaked and reduced, and your water has developed a reading for nitrates.
When your tank tests 0 for both ammonia & nitrites within 12 hours or so of adding the last batch of ammonia - you'll be good to go. Just do a good-sized water change at that point to reduce the nitrates level.

Django 11-08-2012 07:56 AM

I'd like to add another option. If you have a heavily or moderately planted tank, or can buy a lot of fast growers, that's all you have to do. The plants will take care of the ammonia. I did it after my fish food cycle stalled.

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