# Water changes during a tank cycle.



## flyin-lowe (Oct 3, 2009)

Last Sunday I set up a 75g freshwater tank for my grandmother. It has an Aquaclear 110 filter that has been running since Sunday. Tues. morning I added 6 tetras that I got to start cycling the tank. I also added two small anubia's. She just has the standard 48inch strip light with a T8 daylight bulb. 

This morning I added one hornwort plant and some type of sword. ( I can't remember if it was amazon or what.) Anyway I checked the ammonia levels and they were still at zero. How often (if any) should I do water changes while the tank is cycling? I know the ammonia and nitrite levels will shoot up but how high should I let them get before I start doing water changes, or do I need to do them anyway during the cycling process? 
Any other tips for getting the tank cycled without having it take all winter. Also one LFS had the hornwort listed as low light and another had it listed as needing bright light. Does it have a chance to survive in a low light tank?
Thanks


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## WhiteGloveAquatics (Sep 3, 2009)

I set up a tank, I dont touch it till the cycle is over if then I usually wait 2-3 weeks.

Hornwort is a weed, it grows in any light, thrives in high light like most plants.

The cycle should only take 4-6 weeks, see if the LFS has any used filter sponges or gravel, that will kick the cycle quicker and wont last as long maybe 2-4 weeks instead.

The more you mess with em the less stabil they are. I just did a WC for the first time in a solid month maybe month and a half, the readings were better before the change but the fish like the fresh water. There really arent set rules for this, you are going just fine, during the first 2-3 weeks test it every other day, then from 2 weeks on twice a week then the last week once, I would get another smaller aqua clear on it as well, just as a kicker filter but this also allows more good bacteria colonize and keep the water levels in check.

This is what works for me, always has always will. pretty much set it up, get it running then "forget" about it so to speak for a while. Obviously pay close attention to the plants before the fish, the plants are kinda like coal miners canaries.


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## Oldman (May 25, 2009)

I must greatly disagree with WhiteDevil, much as it pains me to do so. You need to do water changes whenever you find levels of ammonia or nitrite approaching 0.25 ppm levels in the tank water. Lets get back to basics, shall we?
Ammonia is a deadly poison to fish and the actual concentration that causes damage to fish varies quite a bit with the pH of the water. The concentration that fish can tolerate goes up quite high when the pH is low but a concentration of 0.25 ppm is tolerated at most of the pH levels you are likely to see. A similar 0.25 ppm of nitrite can be tolerated by most fish but again pH affects the toxicity. This time it works the other way around. At low pH fish are more sensitive to high nitrite levels than at higher pH levels. In most situations, a level of as much as 0.25 ppm is not harmful at typical aquarium pH levels. Beware that nitrites affect fish in much the same way as carbon monoxide affects people. Even with plenty of oxygen available, nitrites can prevent enough oxygen being absorbed by the fish to cause them to act as if they are not getting enough oxygen. They will be gasping for air no matter how well the water is oxygenated. 
Now that we know the effects on the fish, how does the cycle work? It is really quite simple. Bacterial colonies will develop in any location that gets lots of oxygenated water flow and some ammonia that can process ammonia into nitrites. Unfortunately, each 1 ppm of ammonia becomes 2.7 ppm of nitrites. In a similar fashion, bacteria will develop in high flow, well oxygenated locations that will process nitrites into nitrates. Now the ratio continues to build and each 1 ppm of ammonia ultimately becomes 3.6 ppm of nitrates. Fish tolerate high nitrate levels fairly well so we target about a 20 ppm increase of nitrates above tap water conditions as the value of nitrates that we will allow in our tanks. 
What does all this basic information mean to a practical situation? Again it is not a big mystery. The place in a typical aquarium that has lots of surfaces exposed to high flows of well oxygenated water is the filter media. The bacterial colonies will primarily build in the filter media. 
What does all this mean to water changes? Simply put, if you do not maintain poison levels of ammonia and nitrites below 0.25 ppm, as measured using a liquid reagent type test kit, you will have some damage to the fish going on. Doesn't all the water changing inhibit growth of the good bacteria? No it does not. If you find a level of ammonia or nitrite that you can measure, there is more than enough ammonia or nitrite present to cause the respective bacterial colony to grow larger. Any time you can measure nitrites or ammonia, a water change will not slow the growth of the desired bacterial colony but it may well save the health of the fish. If you always treat the fish's health as your top priority on a fish-in cycle, the cycle will proceed at the maximum rate and the fish will be as healthy as you can reasonably expect when exposing them to less than ideal water conditions.


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## flyin-lowe (Oct 3, 2009)

Thanks
That is one of the ?'s in my head was if the clean water will slow the growth of the good bacteria.


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## Oldman (May 25, 2009)

Fresh water will never prevent the fish producing new ammonia by having water flow past their gills and by creating waste that decays in the tank. The exchange at the gills and the organic material decay are a constant supply of ammonia in even the most mature of tanks. The fact that a mature tank can deal with the ammonia as it is created does not mean that it does not exist. A water change can, at most, remove the surplus at the moment that it is done. 5 minutes later there will be newly created ammonia in the tank at low levels to feed your growing bacterial population.


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## beaslbob (May 29, 2009)

In a planted tank with sufficient plants there will be no ammonia or nitrIte spikes. The plants prefer to consume the ammonia over nitrates. So there can be an initial nitrate spike. The 3 weeks later as bacteria have built up and consume the ammonia, nitrates will drop down as the plants are "forced" to get their nitrogen from nitrates.


my .02


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## WhiteGloveAquatics (Sep 3, 2009)

Oldman is correct on the ammonia, however the more WC's I did on this certain tank the more the levels went out of wack.

I use live plants to alert me to the issues in the tank.

I just set em up, check em the first 2 weeks then let them be.


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## flyin-lowe (Oct 3, 2009)

WhiteDevil said:


> Oldman is correct on the ammonia, however the more WC's I did on this certain tank the more the levels went out of wack.
> 
> I use live plants to alert me to the issues in the tank.
> 
> I just set em up, check em the first 2 weeks then let them be.


Are you saying you consider the tanks cycled after two weeks? I have always hear more like 4-6 weeks, and 2 weeks would be the exception. Just curious.


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## flyin-lowe (Oct 3, 2009)

I just stopped in my grandmothers house and did some water tests. The ammonia tested between .25 and .50 ppm. The nitrites tested zero and the nitrates tested 5 ppm. The four live plants I put in earlier in the week all looked really good. 
I am new to the water chemistry part of this but felt it was odd to have a positive test for ammonia and nitrates but not nitrites. Is this normal or did I not get a good reading?


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## flyin-lowe (Oct 3, 2009)

Wednesday I tested the water and it was ammonia .25-.50, nitrites 0, and nitrates about 5. Thursday and Friday ammonia and nitrites were both 0. How many days in a row with a 0,0, reading for ammonia and nitrites should I see before I consider it cycled? It has just been two weeks which I think is quick but I have a few live plants which I understand from others can keep me from having big spikes in those levels.
The first week with the tank I was not able to test the water so I am not sure if there was ever a slight nitrite spike or not. She has also been doing 1 light feeding per day.


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## aquaman (Feb 16, 2009)

I did 25-50% water changes when i cycled my tank every week for 6-8 weeks and eventually my tank was fine.


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## Oldman (May 25, 2009)

In a mere 2 weeks, you do not have a cycled tank at all. You may have enough plants to deal with the present fish load but that is not the same thing at all. Some of the more enthusiastic plant people who run high numbers of fast growing plants do not bother to cycle a new tank because they know enough about growing plants to never have any ammonia able to show up in a test. What works for them seldom works well for a person new to the hobby. If your plants are able to control the ammonia levels in the tank, that is great. In another month or more you may be able to just assume that a cycle has taken place and ease the fish numbers up a bit. When you do that, make sure you test just in case you are still not cycled yet.


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## James0816 (Jun 19, 2009)

You have a couple of things working for you and against you.

First, the size of your tank and your stocking. With only (6) little fishies in there, it isn't going to be so bad.

Using plants to assist....not enough in there to matter. Even with the fact that you have Hornwort which is a nutrient sponge.

Second, you're doing a fishy cycle. Very important to stay on top of the NH3! At your levels right now, you should be doing 25% wc/wk. Again, with your stocking levels, you won't have to be worried about doing more as there just isn't sufficient load on the system.


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## beaslbob (May 29, 2009)

As I understand it you have a few plants, a single 48" strip light, .25-.5ppm ammoina, 1/2 dozen fish all in a 75g tank.

1) don't add any food until ammoina drops down.

2) if nitrItes spike continue not adding food until they drop down also.

3) Ignore any nitrAte readings.

4) Add a 4' 2 tube utility shop light with 6500k tubes ($14) from home depot/Lowes.

5) add anacharis and vals and like 10 bunches/plants each.

6) don't do water changes

7) if the tank clouds up or algae starts showing up, Kill the lights for a few days. then continue with less duration lighting and feeding.


During the cycle period you need to limit the bioload (food) so the plants can keep up. Then over weeks bacteria will build up and finally the plants will be forced to consume nitrates because that is the only nitrogen available. During that time ammonia and nitrItes will be low to 0 by the combined plant and bacteria action. Initially by plants then later by bacteria.



my .02


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## Oldman (May 25, 2009)

I was with beaslbob on this one right up until he said no water changes. Water changes are the difference between healthy fish, long term, and short lived fish that we end up blaming on excessive in breeding or Asian fish farm breeding or any number of excuses. My fish do not die in my tanks ever in the first year that I have them. They instead stay healthy, whether or not I get them from questionable sources. I am a firm believer in doing a large, 90% or more, water change whenever I see something wrong with my tank in terms of water chemistry. That is just as true during a fish-in cycle as it is at any other time. I recently had a problem with a filter that had been running as an extra on an established tank. When I moved it to a new tank to serve a mere 4 fish, I found that it was allowing some nitrites to build in the tank. I drained enough water from that tank that the juvenile mollies in the tank were having trouble swimming before I refilled it. It took only about 4 days for the nearly cycled filter to finish cycling but each day I repeated that water change. I call it a 90% water change when asked about it but I doubt I really left 10% of the tank water behind when doing that change daily. Today, 4 months later, those same mollies are all healthy and growing well. I think that water changes are the key to fish care when things are not going well.


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## flyin-lowe (Oct 3, 2009)

As someone stated earlier after three days of 0 ammonia the levels started to rise again. I did a 20% water change on Monday night and before the change the ammonia was at .50. I went back down today and tested the water again. The levels were between .25 and .50. I did a 25% change today. I was told to keep doing water changes when the level gets close to .50. Also the nitrites are still at zero. How long does it typically take to start seeing some nitrite levels rise. I know they are toxic but I assume that this is an indicator that the tank is cycling. It will be three weeks this Sunday since the tank was started. 3 weeks on Monday since fish and plants were added.


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## Oldman (May 25, 2009)

A "typical" cycle will take about 2 to 3 weeks of ammonia rising before the ammonia starts to take care of itself. At that point nitrites will become the controlling factor in how big and how often water changes are done. The nitrite spike often takes about twice as long to exhaust itself as the ammonia phase did. Once nitrites become the main problem, look back at how long you were dealing with ammonia problems and double it. It is the main reason that we try to get people to do a fishless cycle. A fishless cycle means no water changes unless tank pH crashes and then only enough changes to restore the tank pH. The total time involved in either method is he same but a fish-in cycle causes a lot more stress for the fish keeper.


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