I've talked a bunch about filter bacteria before, but here's a summary for you who missed it.
Fish make ammonia when they live.
This ammonia is toxic to them.
Without a filter, you need to change all of the water in your tank to get the ammonia out.
There are bacteria you can grow that can convert the ammonia into less toxic wastes.
This lets you change only part of the water.
There are two colonies of bacteria that you grow when you make a successful biological filter.
One group converts ammonia into nitrite.
Nitrite is more toxic to fish than ammonia
The second colony converts nitrite into nitrate
Nitrate is much safer for fish to live in than ammonia.
So these bacteria take a while to grow. The first group, that makes nitrite, grow faster than the second group. This means that, while the bacteria are growing, your water will have waste products in your tank that are more dangerous than not having a filter.
The dangers of nitrite spikes are why you should not filter a tank under 2.5 gallons. If you have no filter, the only risk to your pet is ammonia. If you are filtering it, and part of your colony dies (which happens is smaller water volumes because there are fewer resources to go around), your fish are now exposed to more dangerous wastes.
So, how do you grow the bacteria without harming your fish?
First, you're going to want to make sure you have a place for your bacteria to live. If your filter only came with a carbon pad, you're going to want to find a way to put more growing space for the bacteria.
Find the canister filter media/bulk filter media section of your pet store. In this section, you'll be able to find ceramic pellets or noodles (Fluval brand name: Biomax) or filter sponge/filter foam. Now all you need to do is find a way to put that into your current filter, so that water is running over it. I like to keep the carbon pad in the filter, because the filter floss in the pad can help remove particles in the water, and because the filter is often designed with the idea that the pad will regulate the water flow.
If you have a sponge filter, you've already got your biological media. If you have an undergravel filter, your gravel is your biological media.
Some people are going to tell you that you can't leave a carbon pad in your filter forever because it will "leak toxins back into the water."
Who's up for betta fish myth busters?
1) The way activated carbon works is basically that every piece of carbon is constructed with a lot of holes in it and a very high surface area, and an electrical charge. The charge draws certain things to the carbon, and those things lodge in the holes and stay put. Carbon stops being effective when all of the holes have filled up.
2) If you have a brita pitcher in your house, you might have noticed the warning to always change your filter on time. This is because carbon that has filled up can breed bacteria, and if you're a human drinking water you really don't want to be drinking bacteria growing in carbon.
3) Full activated carbon does not let go of what it has collected. Even if it did, the only toxins it would have collected are ones from your tank, ones that would be in your water if you didn't have carbon. So, yes, your carbon is going to grow bacteria in it, once it's full. Do you know what kind of bacteria? Nitrifying bacteria. The kind of bacteria we're trying to grow anyway.
So stop fucking telling people carbon leaches stuff into your tank, because it fucking doesn't.
Okay. So. You have a good place for your bacteria to grow. It's somewhere porous. Now you have to make sure that there is a source of oxygenated water moving over your bacteria. These bacteria need fresh water, water with oxygen, or they die. Almost all filters are designed to draw water through them, so make sure wherever you stuck your biomax or foam is getting water flow.
Make sure to dechlorinate your water with a water conditioner (I like seachem prime, but Tetra's Bettasafe is cheap and available everywhere), because the chlorine in your water can kill your bacteria.
Now you have a good place for the bacteria to grow. So, where do you get them?
All water has small amounts of these bacteria. There's small amounts in the air. If you keep your filter running, and you feed the bacteria what they need, they'll grow.
You can go to the hardware store and pick up some 100% pure ammonia (the kind that doesn't foam when you shake it) and add some drops of it to your water.
You can put a piece of shrimp in a cup of water and leave it there for a few days, and then dump that water in the tank. The shrimp will decay in the water and produce ammonia.
Don't intentionally add ammonia if there's a fish in your tank.
Or you can put a fish in the tank and watch your water parameters like a hawk. This will be between two weeks and two months of frequent water changes.
If you don't want to wait and grow the bacteria slowly, you can speed it up in a couple ways:
You can buy bottled bacteria. Some brands out there don't work and some do. I've had good luck with Tetra SafeStart+ and bad luck with Tetra SafeStart. Fluval makes a decent bottled bacteria.
The other brands usually have anaerobic bacteria in them, which can cycle your tank for a short while before dying. Anerobic bacteria products generally do not get your tank to cycle faster than the slow-cycle method.
Or you can beg/borrow/steal some bacteria from someone's established tank.
There's a few ways you can go about this. If you're putting biomax in your filter, and you know someone who has biomax in their filter, you can ask if you can trade a small handful of your uncycled biomax for their biomax with the bacteria on it. If you only take 1/3rd or less of theirs, their cycle won't crash, and you'll have bacteria to give your cycle a boost start.
You can loan them some filter media or your whole filter, and have them run it alongside their filter. After about a week or two, the bacteria in your friend's tank will have also taken up residence in your filter, which you can put into your tank and have your cycle.
If that doesn't work, ask if you can borrow a porous decoration from their tank: a handful of gravel, the pink castle cave, a silk plant, or something similar. While there won't be as many bacteria on this, there will be more than there are in your unestablished tank, and it can cut cycling time down by quite a bit. When I'm borrowing decor from someone's tank, and I'm cycling with a HOB that has the room, I just shove whatever I borrowed into the filter like it's normal media. If I have gravel, I put it in some pantyhose, knot it tight, and cut off the excess. This keeps all the gravel in one place. Being put in the oxygen-rich water will help whatever bacteria are clinging onto it to grow faster.
What doesn't help a tank cycle faster is taking water from it. The bacteria you need to make a tank's biological cycle complete doesn't live in the water. It lives on hard and porous surfaces in your tank.
If you already have your fish, and you don't have a cycle, read here:
So, there's a couple things you can do. If you don't have fishkeeper friends to steal the bacteria from, you're going to need to build your cycle from scratch.
Some people say you can do a fish-in cycle. This is where you leave the filter running with the fish. Every day, you need to test your water for ammonia, nitrite, and nitrate. You need to use an accurate liquid test kit for this, and you need to change the water every time one of those toxins gets to an elevated level (0.5 for ammonia, 0.25 for nitrite). The changing of the water will slow down your cycling, but it's the only way to cycle with the fish in the water and keep the fish safe.
I don't like that method.
It is much safer to let the fish live in an unfiltered tank for a while. I like to buy a plastic shoe box (big tupperware, sterilite bin, 1.5gal pitcher...it depends on the size of the filter). Then I hook the filter up so that it can run in that bin. Then I get another source of ammonia and add that to the bin. The advantage of this is that I can add ammonia in the cycling tub until it's at 4ppm, which is too high for a fish to live in, but provides the bacteria with ample food. Letting the bacteria live in a high ammoina/nitrite environment makes them grow faster. When you can add enough ammonia to bring the tank to 4ppm before bed, and wake up to 0ppm, your filter's well on its way to being cycled. This usually takes a couple weeks, but it depends on your water, the temperature of your water, how much ammonia you put in it, and a few other factors.
As for how to know if your tank's cycled, you're going to need a way of testing your water parameters. I like the API liquid test kit master freshwater kit. It's about $30. If you're cycling with the fish in, you need a liquid test kit, because test strips can stop being accurate if they're exposed to air. If your fish is directly at risk, you need the precision you know you get with a liquid kit.
If you're cycling outside of your tank, you can use the API 5-in-1 strips and an ammonia test strip. When you're buying test strips, always get the smallest package you can, because being exposed to air will reduce the accuracy of your strips. However, if you're cycling outside of your fish's environment, you don't need extreme accuracy. All you need is to see that when your cycle's done, you have no ammonia and no nitrite, and a good level of nitrates. When that's happened, remove the filter from your cycle tub and put it in your aquarium (but don't add any of the cycling water).
The liquid test kit comes out cheaper in the long run, BTW.
But this looks hard and I thought having a fish was easy.
If you think you're going to just put your fish in with the filter and change the water a lot, because you don't want to get some water tests, here's what you can do:
First of all, save up for some water tests. Any time your fish is sick, you should test your water. Most of the time, the cause of your fish's sickness is incredibly obvious when you test his water.
Second, because you can't measure your ammonia level in the water, you have to be careful adding it. Get 20% ammonia (which is available at the hardware store) and add 1 drop for every 2/3rds of a gallon of water you're cycling the filter in. This should get you to 4ppm. You cannot go higher than 8ppm or you'll start killing your filter bacteria. They can only tolerate so high of levels.
Now add 1 drop every 3 days for 2 weeks. At the end of 2 weeks, add a drop, and 12 hours later take a water sample to your pet store. Most pet stores (including petsmart) will test it for free. If you have no ammonia, no nitrite, and a good nitrate level, you're good! Make sure you let the employee know that you're cycling the tank without a fish, or they might panic at your nitrate level.
Remember that you still need to change the fish's water while your filter is cycling.
<Insert witty final remark>