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Discussion Starter · #1 ·
Hey all,

I'm new to this site and I love it! I've yet to do much other than pick through all the incredible info that's constantly streaming in. And thank you all for contributing so much of your knowledge!

I have a question that I think fits under this category, but I'm sorry if this is the wrong place.

So I made a sponge filter with a power head on it. Nothing too fancy, and I'm getting it ready to put in a 20gal I recently acquired. I've been reading various posts on sponge filters and some are saying it will take close to a month for the beneficial bacteria to build up in the sponge to the point that it would be ready for fish. That's a long time to just let the filter run in a new tank.
So I got an idea. I thought that maybe if I setup and ran the filter in my better established tank, its about 3ish months old, that the bacteria, already being in that tank, might build up faster in the sponge. I'm waiting for the silicone to cure on the other tank anyway (had to plug a hole)

Will this help speed up the process of growing the necessary bacteria? Or am I just wasting my time and electricity? Thanks in advance for any thoughts!!

189 Posts
If you have another sponge filter set up in your established tank you should rinse it out in a small container of tank water and then put the new sponge in that water and squeeze it a few times to disperse the bacteria all over the new sponge. That will help too.

11,721 Posts
Think of it this way:
No matter how many or how few fish are in the established tank, they only support X amount of bacteria.

If you run the new sponge on the existing tank some bacteria will start to grow on it, and some will start dying off in the current filter. Not much, but some.

When you remove the newly cycled sponge you are removing some of the bacteria that should have stayed with that old tank.

If you only run the new sponge for a few weeks there will not be so much bacteria on that sponge. Removing it will not cause problems for the old tank, but it will also not have a lot of bacteria for the new tank.

Here is what I would do:
Run the sponge in a container with no fish, and do the fishless cycle in that bucket. This will grow the maximum population of bacteria in the shortest time, without an risk to the established tank. You can clean the old filter media into this bucket to jump start the bacteria. Mostly the bacteria grows stuck on surfaces, and stays stuck even when you clean the media, but you can get enough from the dirty filter to jump start a new filter.
Here is the fishless cycle:

Fishless Cycle
You too can boast that "No fish were harmed in the cycling of your new tank"
Cycling a tank means to grow the beneficial bacteria that will help to decompose the fish waste (especially ammonia). These bacteria need ammonia to grow. There are 3 sources of ammonia that work to do this. One is fish. Unfortunately, the process exposes the fish to ammonia, which burns their gills, and nitrite, which makes their blood unable to carry oxygen. This often kills the fish.

Another source is decomposing protein. You could cycle your tank by adding fish food or a dead fish or shellfish. You do not know how much beneficial bacteria you are growing, though.

The best source of ammonia is... Ammonia. In a bottle.

Using fish is a delicate balance of water changes to keep the toxins low (try not to hurt the fish) but keep feeding the bacteria. It can take 4 to 8 weeks to cycle a tank this way, and can cost the lives of several fish. When you are done you have grown a small bacteria population that still needs to be nurtured to increase its population. You cannot, at the end of a fish-in cycle, fully stock your tank.

The fishless/ammonia cycle takes as little as 3 weeks, and can be even faster, grows a BIG bacteria population, and does not harm fish in any way.

Both methods give you plenty of practice using your test kit.

How to cycle a tank the fishless way:

1) Make sure all equipment is working, fill with water that has all the stuff you will need for the fish you intend to keep. Dechlorinator, minerals for GH or KH adjustments, the proper salt mix, if you are creating a brackish or marine tank. These bacteria require a few minerals, so make sure the GH and KH is at least 3 German degrees of hardness. Aquarium plant fertilizer containing phosphate should be added if the water has no phosphate. They grow best when the pH is in the 7s. Good water movement, fairly warm (mid to upper 70sF), no antibiotics or other toxins.

2) (Optional)Add some source of the bacteria. Used filter media from a cycled tank is best, gravel or some decorations or a few plants... even some water, though this is the poorest source of the beneficial bacteria.
Bacteria in a bottle can be a source of these bacteria, but make sure you are getting Nitrospira spp of bacteria. All other ‘bacteria in a bottle’ products have the wrong bacteria. This step is optional. The proper bacteria will find the tank even if you make no effort to add them. Live plants may bring in these bacteria on their leaves and stems.

3) Add ammonia until the test reads 5 ppm. This is the non-sudsing, no surfactants, no-fragrance-added ammonia that is often found in a hardware store, discount stores, and sometimes in a grocery store. The concentration of ammonia may not be the same in all bottles. Try adding 5 drops per 10 gallons, then allowing the filter to circulate for about an hour, then test. If the reading isn't up to 5 ppm, add a few more drops and test again. (Example, if your test reads only 2 ppm, then add another 5 drops) Some ammonia is such a weak dilution you may need to add several ounces to get a reading.

4) Test for ammonia daily, and add enough to keep the reading at 5 ppm. You probably will not have to add much, if any, in the first few days, unless you added a good amount of bacteria to jump start the cycle.

5) Several days after you start, begin testing for nitrites. When the nitrites show up, reduce the amount of ammonia you add so the test shows 3ppm. (Add only half as much ammonia as you were adding in part 4) Add this reduced amount daily from now until the tank is cycled.
If the nitrites get too high (over 5 ppm), do a water change. The bacteria growth is slowed because of the high nitrites. Reducing the level of ammonia to 3 ppm should prevent the nitrite from getting over 5 ppm.

6) Continue testing, and adding ammonia daily. The nitrates will likely show up about 2 weeks after you started. Keep monitoring, and watch for 0 ppm ammonia, 0 ppm nitrite and rising nitrates.

7) Once the 0 ppm ammonia and nitrites shows up it may bounce around a little bit for a day or two. Be patient. Keep adding the ammonia; keep testing ammonia, nitrite and nitrate.
When it seems done you can challenge the system by adding more than a regular dose of ammonia, and the bacteria should be able to remove the ammonia and nitrite by the next day.
If you will not be adding fish right away continue to add the ammonia to keep the bacteria fed.

8) When you are ready to add the fish, do at least one water change, and it may take a couple of them, to reduce the nitrate to safe levels (as low as possible, certainly below 10 ppm) I have seen nitrate approaching 200 ppm by the end of this fishless cycle in a non-planted tank.

9) You can plant a tank that is being cycled this way at any point during the process. If you plant early, the plants will be well rooted, and better able to handle the disruption of the water change.
Yes, the plants will use some of the ammonia and the nitrates. They are part of the nitrogen handling system, part of the biofilter, they are working for you. Some plants do not like high ammonia, though. If a certain plant dies, remove it, and only replace it after the cycle is done.

10) The fishless cycle can also be used when you are still working out the details of lighting, plants and other things. If you change the filter, make sure you keep the old media for several weeks or a month. Most of the bacteria have been growing in this media (sponges, floss etc).
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