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120g fishless cycling questions
Posted: Wed Mar 14, 2007 2:55 am
by spoot
Questions about fishless cycling.
Background info: We are doing it with the method of putting food in the tank and letting everything run it's course. At fist we used marine about 5 cubes of frozen marine mix for about 2 weeks but the tank got really ugly with all the bits of decaying food lying everywhere. So we vacuumed out all of it and did a 50% water change. The tank sat empty for 3 days then 1 piece of left over prawn was placed into the tank. There was pretty much most of the prawn left since our babies are small and can't eat that much. Now, days later, the prawn is covered happily decaying and feeding our bacteria.
Current situation: The tank currently now still has ammonia and nitrites.
Questions:
1) Is the prawn supplying enough ammonia to keep the cylce going?
2) Is the prawn making too big of a bio-load such that the bacteria can't keep up and thus the reason for the ammonia and nitrites
I think that's it so far from I can think of now. Thanks everyone, hope to get our puffies in soon. I know they'll just love it.
Posted: Wed Mar 14, 2007 3:00 am
by Nusquam
Just wanted to add, in case people are too lazy to do the math, the prawn's been in there for about 10 days now, and we tested the water yesterday.
Results:
Ammonia: 0.25-0.5
NitrIte: 0.1-0.3
NitrAte: 0-10 (can't remember exact number, we tested 3 tanks yesterday >.<)
Posted: Wed Mar 14, 2007 3:46 am
by Rocker
You would be better of buying some ammonia solution and following an article. This method for me is a bit hit and miss. Once the tank has cycled you will not be sure that it could handle the bioload of the fish in the tank.
Posted: Wed Mar 14, 2007 9:11 am
by Boxermom
I personally like the shrimp method. However, I'd recommend for a tank that size adding several more pieces of shrimp to ensure a sufficient bacterial load.
Posted: Wed Mar 14, 2007 11:11 am
by Peregrine
Rocker wrote:You would be better of buying some ammonia solution and following an article. This method for me is a bit hit and miss. Once the tank has cycled you will not be sure that it could handle the bio-load of the fish in the tank.
I agree with the idea of using ammonia instead. The ammonia production with shrimp tends to start off slow, peak and then fall as the shrimp decomposes...you cannot control the ammonia level (or keep it constant) through out the cycle. Even if the tank cycles...your cycle is finishing up at the point where the ammonia production is likely at its lowest...Like Rocker said..it may not be high enough to support the initial fish introduced. There is even the possibility the cycle can stall.
I prefer a little more control over the process...
Is this your Ceylon tank...What SG are you cycling it at?
(I mean, you are not cycling at full marine are you? (it changes the approach if you are)
Posted: Wed Mar 14, 2007 1:26 pm
by spoot
Peregrine, yes, this will be our ceylon tank. We are cycling at 1.012. We raised the SG a bit fast compared to our fish's size because our hydrometer let us down (or up

) . Now we have a refractometer and just love it!
The ammonia method seems like a lot of hassle though. It takes 5 minutes for our ammonia test to complete. So to get the correct amount of ammonia, we would have to test multiple time when adding it and it would end up taking a very long time. Especially if we need to test everyday, multiple tests each time.
If we were to switch to the ammonia method, would you suggest we start out the ammonia dosing from the beginning of the regime?
Thanks for the replies

Posted: Wed Mar 14, 2007 3:03 pm
by Rocker
NO hassle for a 5 min test daily to ensure your filter is cycled.
With the prawn method you will never know if it has cycled with enough bacteria to support the puffer you are putting in the tank.
Posted: Wed Mar 14, 2007 3:22 pm
by spoot
Has anyone tried calculating the amount of ammonia needed to raise the tank to a certain PPM?
We should be testing before we add ammonia to see how much there is left in the tank right? Then we add ammonia and test again to see if we added enough or too much. If the amount is incorrect, then more ammonia needs to be added and the water needs to be tested again.
I could calculate it, theoretically, but at the moment I don't have the time. Maybe just add more prawns?
Posted: Wed Mar 14, 2007 4:36 pm
by Peregrine
Five min!!!...my test takes 20 min...now there was some wasted time...
To get a dose giving a givenn ppm would depend on the type/concentration of ammonia used.
Not really that big of a hassle...after the first little while you get a "feel" for it and dosing becomes easier
Posted: Wed Mar 14, 2007 5:19 pm
by RTR
Commercial ammonia preparations vary in strength, and the material decomposes a bit in storage (not as fast as peroxide does, much slower). You could roughly calculate the strength by how much is required for the initial doses - it is stable enough to hold through the few weeks of fishless cycle.
If you have not checked the ammonia and nitrite titers routuinely during cycling, whether ammonia or meat or fish food, then you really do not know whether or not the tank is cycled, do you?
Posted: Wed Mar 14, 2007 7:07 pm
by Nusquam
I check the parameters of all the tanks at the very least once every 2 weeks. Usually it's once a week unless something comes up, so I am keeping an eye on it. The ammonia seems to have peaked at about 0.5. If it needs to be higher I can throw a couple more things in there. That's if, the puffs are ok with eating more prawns, being such picky eaters and all

Posted: Thu Mar 15, 2007 3:30 am
by Rocker
I am still not sure what you guys are hoping to achieve by dding the prawns.
Yes the tank will cycle eventually but will it be enough to support the puffer. You will not know and then the tank might have to cycle again once you add the puffer. Like I said it a bit hit and miss.
Posted: Thu Mar 15, 2007 9:16 am
by Boxermom
I've never had a problem using shrimp and neither has anyone else I know. There's not much difference IMO between not knowing if there's sufficient bacteria with ammonia or shrimp. Either way, how can you measure it? If you use a sufficient amount of shrimp for the size of the tank and the expected bioload (i.e., more than 1 small piece in a 120g expecting puffers), it shouldn't be an issue.
Posted: Thu Mar 15, 2007 10:29 am
by Rocker
Boxermom wrote:I've never had a problem using shrimp and neither has anyone else I know. There's not much difference IMO between not knowing if there's sufficient bacteria with ammonia or shrimp. Either way, how can you measure it? If you use a sufficient amount of shrimp for the size of the tank and the expected bioload (i.e., more than 1 small piece in a 120g expecting puffers), it shouldn't be an issue.
I think that you have missed the point of fishless cycling with ammonia. It is a very precise way of cycling and ensures that your filters are loaded with enough bacteria to more than fully support a complete tanks worth of stock.Something I can't see the prawn method doing as effectively if at all.
Measurements are taken daily and the ammonia is topped up daily if needs be to ensure the maximum amount of both colonies are develpoed.
To me there is a world of difference in using a prawn to measuring an exact amount of ammonia that has proven results.
How many prawns do you need to cycle and fully stock a tank?
Posted: Thu Mar 15, 2007 11:27 am
by RTR
I'm w/Rocker. I had rather know that I have more biocapacity than I will need.
Even though I rarely cycle a tank from scratch (having spare filters is a dandy luxury), I am still likely to ammonia-challenge a new setup to confirm the capacity. I do turn the lights off during that challenge if the tank is planted.