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Originally Posted by stephanieleah  Okay, let me distill this. Low nitrate = healthy, cycled tank because plants are using nitrate in addition to ammonium which they convert from ammonia (?). My ammonia reading may be coming from ammonium because some of the water I added with my pleco had ammonia detoxifier in it. I thought it was better not to detoxify the ammonia for some reason or other. With the bio filter still build up bacteria if there is ammonium?
And just to get it straight, I should still do a 30% water change (I have one brand of chorine, choramine, and ammonia detoxifier, don't know off hand but it's in a yellow bottle). What do we do water changes for anyway? And how do I know when and how much water changing to do?
You guys are awesome, I love all the feedback. It makes me feel like this whole forum is about me :0) which it is in my limited little fishy microcosm over here.
By the way I haven't looked at the water link, Angel...maybe I should brace myself! |
I'll just follow-up and detail some of what subsequent posters have mentioned since it is very important. First on the ammonia and nitrification cycle, second on partial water changes.
In a planted tank a low nitrate reading that is consistent means the biological equilibrium is working. Other things can still go wrong, like an increase in ammonia from this or that, but most of us find that once a tank is established (3 months and beyond) it tends to be stable unless we do something to interfere with the biological equilibrium (adding too many fish, mega overfeeding, dying fish and plants, chemicals that kill off biological organisms, etc).
Ammonia is highly toxic to fish and plants and will kill both if left as ammonia. Fortunately, plants grab it and convert it to ammonium to use for food, and nitrosomonas bacteria will establish themselves and use ammonia or ammonium as food and nitrite is the result, then nitrite is used by nitrospira bacteria or perhaps plants, and nitrate results from the bacteria. Plants can use nitrate by changing it back into ammonium for food, but they "prefer" to use ammonium or ammonia for this. Whatever occurs, either way, the end result is a low nitrate reading.
Nitrosomonas bacteria use ammonia and ammonium in the nitrification process; in a planted tank the plants use most of it so the bacteria will be less than in a non-planted tank.
When you do a partial water change, if there is ammonia in your tap water, you want to use a good conditioner that will detoxify the ammonia; they do this by changing it into the less harmful ammonium. The plants and bacteria still use the ammonium, but if the ammonia was just added without the detoxifying conditioner, it would be a sudden onslaught of highly toxic ammonia and that would stress and possibly seriously damage the fish.
Now to the partial water changes. The
only reason to do a pwc in a planted aquarium is to rid the tank of toxins that build up and cannot be effectively removed any other way. These toxins are urine and solid waste from the fish. No filter will remove these, period. Plants can, but it is a slow process and only effective if the fish load is very minimal and there are many plants. One author used the example of 6 or 7 neon tetras in a 55g tank that was heavily planted as being the upper limit. Most of us have far more fish in our tanks that this, so we need to do the pwc to remove the pollution. If a well-planted aquarium has a small fish load, fewer pwc's will be needed; Diana Walstad writes of doing one every few months, and that works if the fish load is not beyond the capacity of the plants and biological system. Again, most of us have more fish than the system can support without our assistance via the weekly pwc. In non-planted tanks, the pwc also dilutes/removes nitrates, but this is irrelevant in a healthy planted tank because the plants consume the ammonium, and nitrates are therefore minimal.
It is frequently said that the pwc should be more frequent with less water in order to sustain stability in the water quality. In a planted aquarium the plants are doing the major filtration and the water is, as I've indicated above, going to be stable if everything is working the way it should. So that leaves us with the pollution (toxins). The more water changed, the more pollution is removed, plain and simple.
In the November issue (2009) of TFH there is a good article on this. The author ran tests and explains why changing more water is preferable to changing less water. Pollution accumulates daily (the waste from the fish is steady) and every day an equal amount of waste is added. In other words, the toxins are increasing far more as each day goes by, so each day there is a high percentage of pollution in the aquarium. In contrast, changing 50% once a week is cutting the pollution in half, with the result that day by day the pollution will gradually increase toward the end of the week; in other words, the fish are only going to be subjected to very high levels of pollution at the end of the week just before the 50% water change, so during the previous days they are exposed to slightly less pollution that they are with a daily 10% water change. OF course, changing 50% or more each day would be ideal. But most hobbyists can find it easier to maintain a regular weekly schedule rather than a daily one.
Coming back to the water stability issue: there is no logic in maintaining more stable pollution in a tank. No one could logically dispute that reducing pollution is a benefit and the more the better. At the same time, a significant weekly water change will actually work to maintain more stability long term in the water parameters.
To sum up, a weekly pwc is the minimum in an aquarium, and changing 50% will be healthier for the fish.
Byron.
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