Cycling a tank

I have a 20gallon tank that I used to keep cold water fish in But unfortunatly a disease killed them all

I've now converted this tank to keep tropical fish and am trying to cycle it before I buy all the fish I want

I've put 3 tiger barb's in the tank just to get things started but its been just over a week and im hardly seeing any ammonia at all in the tank Reading between 0 and 0.25 on my testing kit

Do I just wait a couple of months or do I need some more fish?

Cheers

Oh yeah also some of my stones have a weird yellow/green mold type thing forming on them I havent cleaned them with the vacuum tool because I didnt want to change any water while the tank is cycling but it looks a bit off-putting

- Phil

Water changes will be key during the cycle. With just 3 Tiger Barbs it will take a while for the bio load. Cycling typically can take 4-6 weeks. In the case of my 20 gallon, it took 8 weeks and I had about 10 small fish in it. You won't see ammonia spikes for a while so hang in there. I'm surprised you're even seeing 0.25 only 1 week into it.

Now at the risk of getting flamed in here! LOL!! I cycled a 10 gallon tank using the 'Cycle' product. I have a bunch of White Clouds and a few African Dwarf Frogs in the tank. Using this product as directed cut the cycle time down to about 3 weeks. I change 20% of the water 2 or 3 times a week suring the cycle.

The way I understood it was that changing the water was bad before the ammonia spiked - because it will reduce the amount of ammonia in the tank and slow down the creation of the good bacteria

The website I read said dont do any water changes until your seeing nitrates building up - then do a 10% changes of the water every 1 or 2

Prior to the nitrifying bacteria colony (Nitrosomonas) being large enough to digest the Ammonia (NH3) in your tank, you may see NH3 levels spike way too high. Even to the point of being toxic to the fish. Water changes keep these levels in check. Typically you won't see nitrates until the end of the cycle. NH3 should spike some, then N02 (Nitrites) will spike. The next colony of bacteria (Nitrobacters) will digest NO2 and expel NO3 (nitrate).

Don't worry if you see your new tank get cloudy (white milky color). This is a bacteria bloom and will clear itself up usually within a week or so.

Up to 40ppm is a typically safe level of nitrates once the tank is cycled. My tanks are at around 20ppm of NO3. NH3 and NO2 are at 0. But it took me 8 weeks to get to that point. That all being said, my next tank I am going to try a fishless cycle using household ammonia and Bio-Spira or Cycle (here come the daggers now!!). I just want to try it different ways and see which way produces the best results. As always with this hobby YMMV. So far I have had excellent results cycling and fish loss has been extremely minimal.

Here's an interesting article about cycling ...

Ahhh I see - so water changes are nescessary to keep the ammonia safe until the bacteria is capable of doing it itself..

Thanks mate!

I think I may risk buying the angel fish I have my eye on...

No daggers! I cycled my first tank (60 litre) with fish, and using Cycle for the first week. It took about 5 weeks, and the tank water smelled like cat's p*ss for a month. I also found that the NO2 levels were slow to peak and even slower to drop, and I had an outbreak of white spot (ich) after 2 weeks, suggesting that the fish were stressed and less than healthy. However, I didn't lose any fish. I did frequent partial water changes (25%), which probably contributed to prolonging the cycling process.

I subsequently cycled another 60l tank and a little 20l hex using the fishless cycling method, seeding the tank with some used filter media and gravel, and adding ammonia. The cycle took 15 days in the 2ft tank, 8 days in the hex. No water changes to do (except one big one before bringing in the fish), and I was able to fully stock both tanks immediately, with no subsequent glitches in water parameters.

Not having tried cycling with fish, but without using Cycle, I can't offer an opinion as to whether the stuff really helps the cycling process or not. However, the fishless cycling approach worked perfectly for me.

Vicki PS

I just did a 38l tank with fish using Cycle. I used it as they suggested and the process took about 19 days. So far so good.

No daggers, but advice. The Bio-Spira product works pretty much instantly. No fishless cycles, adding NH3, etc. It's produced by Marineland, and has a good writeup online at their website. I had to medicate a 90 gallon freshwater tank, which killed all the bacteria. The water changes were getting to me, so I put the biospira into the tank, and went back to the pre-medication tank maintenance schedules. IMO a much better world for the fish to live in.

Eric G

You can always take the cheap way out and just leave a bag of gravel out of another established tank in the cycling one for a week or so..