Water Quality: The First 30 Days (Cycling your tank)
ok... so you have a new tank.
and you've already put fish in it.
Your challenge over the next month to six weeks will be to keep the water from getting toxic while your biofilter bacteria get up to speed. This process is often called cycling the tank.
If you haven't gotten your fish yet, there's a better way to do it. Do a fishless cycle!
So what's going on in my tank during the first month and what are these biobugs?
Fish and the bacteria that eat debris in the tank produce ammonia which is toxic. Until your biofilter bacteria (biobugs) get up to speed, it's up to you to keep the water from getting toxic and killing your fish.
The first set of biobugs that will grow in your tank are the ones that convert ammonia (toxic) to nitrIte (still toxic). It usually takes the ammonia eaters 2-3 weeks to get up to speed to where they can convert ammonia to nitrIte as fast as it's produced. In the chart, you can see that ammonia starts building up and maxes out at about a week, then starts to drop as the ammonia eaters get up to speed. The second set of biobugs that will grow in your tank are the biobugs that convert nitrIte to nitrAte (less toxic). These biobugs start growing around week 3 and take 2-3 weeks to get up to speed to where they can immediately convert any nitrIte produced into nitrAte. In the chart, you can see that nitrIte starts building up and maxes out at about the third week, then starts to drop as the nitrIte eaters get up to speed. |
Note that after the biofilter bacteria are established, nitrAte will keep rising and in time will get to toxic levels. Regular partial water changes (and fast growing plants) will keep nitrAte at tolerable levels.
Ok. What do I need to keep the water happy?
Things that would make the process go faster:
Things that may help make the process go faster:
OK. So what do I do first?
The first thing to do is to draw up and dechlorinate a gallon of tap water and test it for ammonia, nitrIte, nitrAte, and pH. Why? because your source water may contain the things you're trying to keep under control in your tank. My tap water has 2.5ppm ammonia and 10ppm nitrAte. That made it more difficult to keep ammonia down at tolerable levels while my biofilter bugs were getting up to speed.
How toxic ammonia is in your tank depends on your water temperature and pH. Higher water temperature and higher pH make ammonia more toxic. If you pH is 8 you're going to have to work harder at keeping ammonia levels low than if your pH is 7. In general with:
pH=7.0, total ammonia should not exceed 4ppm
pH=7.2, total ammonia should not exceed 3ppm
pH=7.4, total ammonia should not exceed 2ppm
pH=7.6, total ammonia should not exceed 1ppm
pH=7.8, total ammonia should not exceed .75ppm
pH=8.0, total ammonia should not exceed .5ppm
More detailed information on ammonia toxicity, pH, and water temperature is here
How do I keep ammonia under control?
Test your water daily, and use a combination of Amquel or Prime and partial water changes to reduce ammonia levels to below your target levels. That way you'll have room for ammonia to increase before the next partial water change.
Base the size of your partial water changes on how much you want to reduce ammonia. e.g. a 25% partial water change will reduce ammonia from 1ppm to .75ppm (if your tap water doesn't contain ammonia). When you do partial water changes, be sure and dechlorinate and keep the change water temperature to within a couple of degrees of the tank water. When you do partial water changes, just vacuum the surface of the gravel lightly to remove debris--no deep cleaning for now. You can use an extra dose of Amquel or Prime to help lower ammonia even further.
Other things that will help:
If you use Amquel you will need to keep an eye on your pH and may need to use baking soda to keep your pH from getting acidic.
Yea! I'm starting to see nitrIte. What do I do now?
Add salt at 1 teaspoon per gallon of water. Pre-dissolve in tank water and make sure it disperses well when you add it. You can use non-iodized table salt as long as it doesn't contain yellow prussiate of soda. Rock salt is cheap and works well. NitrIte is toxic. It enters thru the gills and binds up the red blood cells keeping them from being able to carry oxygen. Salt helps protect against nitrIte poisoning because it competes with nitrIte for uptake thru the gills. After you get it salted, when you do partial water changes just add 1 tsp of salt per gallon changed till nitrItes come down to 0, then you can skip adding any more salt. Your partial water changes will then remove it over time.
How do I know when my biobugs are up to speed?
When your ammonia and nitrIte are reading 0ppm and your nitrAte is rising your biobugs are up to speed. Be nice to your biobugs tho, cuz they're still touchy. They mostly live in biofilms on surfaces, so avoid disturbing them.
Always rinse your filter in discarded tank water, NOT chlorinated tap water. Be gentle at first. Later after the biofilms has matured, you can whack the heck out of the filter pad to clear it. You'll want to keep using your existing filter pad as long as you can, cuz a lot of your biobugs live there. When it's starting to get stopped up and smacking it is starting not to clear it, put a new filter pad in the tank in addition to your existing filter pad to start colonizing it.
Ya Hooooo! I'm cycled!! What now?
Give yourself a pat on the back! :)
and then...
NitrAte will keep building up, so do partial water changes between 20% and 40% of the tank water weekly. Keep an eye on nitrAte levels and when partial water changes don't bring them down to below 40ppm, do a second partial water change to bring them down. There is leeway on nitrAte levels. I haven't found any studies specific to goldfish, but in one study the reported amount that it took to kill half the Indian major carp tested in 24 hours was 1500ppm. I wouldn't recommend letting it even get close to that high, especially with fancy goldies--Lower is better. After you biobugs are established, if you have gravel in your tank vacuum at least half of it well during each partial water change and rinse your filter in discarded tank water.
Keep an eye on pH, especially if it's 7.5 or lower. As your biobugs convert ammonia to nitrAte they use up KH (buffers that keep pH from getting lower-acidic) and release acids which also tend to lower pH. The larger the fish load in your tank, the faster this process happens. If your pH drops below 6, it can kill both your goldies and your biobugs. If you tap water is adequately buffered (KH at or above 120ppm or 7dh), partial water changes should maintain your pH. If your source water isn't well buffered you will need to use baking soda and/or crushed minerals (e.g. crushed coral, crushed oyster shells, aragonite, etc.) to keep your pH from getting acidic.
and enjoy your goldies!!
They can live 10+ years if you give them a good home. :)