Jump to content

Water Changes: Frequency


roo

Recommended Posts

As someone said earlier the reason why we do water canges is to remove nitrates. Some people say it also replaces vital nutrients etc, but I have never seen and proof of this. Small evaporation top ups would do this anyway.

I find that I never really get any nitrate reading whatsoever, so I rarely do water changes. Say one 30% W/C every 3 to 4 months. Mind you I have plants in my tanks, they are not so heavily stocked, and I only feed lightly. It is a different story if you have a tank packed with hungry tropheus or mbuna. Regular water changes will be crucial in this case.

I think alot of people do too many unecessary water changes, as I know I used to. Most people do not do nitrate tests so they don't know why they are changing the water, or what effect (if any) it may have. If you have 100ppm of nitrate, then doing a 30% change will lower the reading to about 70ppm. In this case 50% W/c's will be more effective. On the other hand if you have 3ppm, then a 30% change will lower it to about 2ppm, why even bother water changing!

Most filters will actually lower nitrate levels anyway. And so will fine gravel beds. The bottom line is get a nitrate test kit, and then you will know what is needed in your circumstances.

Daniel

Link to comment
Share on other sites

Most filters will actually lower nitrate levels anyway. And so will fine gravel beds

Daniel, are you absolutely sure about this? I think you'll find that most filters ARE nitrate producers! As for fine gravel beds, hmm, I think you may need to retract that statement as well.

Link to comment
Share on other sites

I have posted this paper before:

Behavior and Physiology of Nitrifying Bacteria

This should give a full background on the whole process.

The two key bacteria present in the aqua system are Nitrobacter sp. and Nitrospira sp. . (btw. more recent genetic analysis of culture has proven that the common Nitrosomonas sp. are not present in significant numbers).

All these bacteria can survive free swimming (i.e. unattached to a film colony). Some of them are fully mobile (see the paper for discussion on their flagella). They do have a preference towards living in a film colony but plenty do exist in the water. Considering their reproduction rates there will be a lots in substantial volume of well established water, which is why you can see a tank with a tank of used water very easily (something that many of the more experienced fishkeepers here will attest to).

Link to comment
Share on other sites

I find the differences of opinions presented fascinating. I think you have to do what works best for you or rather your fish laugh.gif I personally dont change any more than 50% of my water in any of my tanks in a week. I dont think I need to. I dont pre-age.. however i add the water back in slowly. Works for me....my fish are healthy...grow well.....why change?

I think another point to note which nobody has mentioned yet is to get the amount of food your feeding right. Not too much to pollute your tank & not too little to starve your fish. Then again this mainly applies if you are feeding meaty foods. When i have overfed with Tetra Bits it stains my water..so its all relative. I'm with Ducksta....your bacteria are tougher than you might initially think smile.gif

Link to comment
Share on other sites

Many of the nitrifying bacteria use whip-like flagella to propel themselves through water, akin to an oar which drives a Venetian gondola. However, the environmental engineering literature often suggests that nitrifiers prefer a sedentary, stationary existence, attached to a solid surface rather than freely swimming. In fact, nitrifying reactor systems inherently rely on this adhesive preference. Nitrifiers could only be retained inside process reactors when attached either to a surface biofilm or as part of settleable activated sludge floc

Summary

Ammonia toxicity to fish contained within aquaculture systems can be reliably alleviated with biological nitrification, whereby excreted ammonia is successively oxidized to nitrite and nitrate. Given sufficient space and time, these nitrifiers can routinely scavenge ammonia from a recirculating flow passed over their attached media habitat. However, these microorganism have certain environmental preferences which must be routinely satisfied, including: elevated dissolved oxygen, neutral to slightly alkaline pH, and moderate temperature. Attention must also be given to their interaction with other bacteria, and specifically those who thrive on residual organic matter. These latter microbes can overwhelm the slower growing nitrifiers, overcrowding their niche and stifling their metabolism. These problems, however, can be minimized by providing additional media able to accommodate both groups by spreading their population over a greater, and effectively more viable, surface area.

Though a little too scientific for me, I found the above two paragraphs interesting. I couldn’t find any reference in the article as to when it was written, this may have a great impact on how accurate the finer points of it are. I found it interesting that it states that bacteria can live either as a free swimming, or sedentary lifestyle, and can go from one to the other.

I would still hold however, that if one wishes to start up a new tank, putting water into it from an existing tank will still be a second choice to putting established bio-media in the new tank. I would parallel it with starting a new tank by putting fish in there, which is the “old way” of doing it, which I believe is outdated.

It’s a bit like the chicken and the egg – which comes first? The bacteria or their food (fish waste)?

So, you take a bucket of water out of an old tank, and put it into the new tank. How much bacteria are there? Lots or a little? Who’s to know? Can you put fish in there and reliable know that there are enough bacteria in there to carry on nitrification with out any rise in ammonia? Who knows? How may fish can you put in there? Only actually doing it each time and monitoring it will give this answer, and it will vary each time.

Another point too, if you put a bucket of water from an existing tank, into the new one, the bacteria can only multiply if there is food for them to eat. That is, it’s a new tank, with no fish - no fish, no food, will eventually = no bacteria. So when do you put the fish in? And how many do you put in so you don’t get an ammonia reading?

However, if you take established bio-media out of an old tank, and put it in a new tank, you will be able to fully stock the tank (keeping in mind you must put enough bio-media into new tank of sufficient volume, and you must make sure there is enough left over in the existing tank to carry on with nitrification).

If you transfer bio-media into the new tank, you will have a pretty good idea how much bacteria you have (percentage of the amount of media). That is, you will be able to put in a reasonable stocking level, which will in turn feed the bacteria and allow them to take up any shortfall, with ammonia a very unlikely side effect.

Lv426

Yes there is a lot of different opinions, but if one thought through the variables that need to be taken into account, there are better ways of doing things. So yes, what you do may work for you, but that doesn’t mean you can’t do it better.

Daniel

Most filters will actually lower nitrate levels anyway. And so will fine gravel beds. The bottom line is get a nitrate test kit, and then you will know what is needed in your circumstances.

A properly maintained filter will produce nitrate. If you filter is reducing nitrate it means you need to clean it. Yes a planted tank is a bit different from a fish tank, as plants in great enough numbers will use all the nitrate in the tank, and the aquatist will in fact have to add nitrate to the tank.

And the amount of nitrate that is reduced by the anaerobic bacteria in the gravel will be greatly overwhelmed by the nitrate being produced as the end result of feeding your fish. And in fact this will also be dependant on how deep your gravel is. If it it shallow, there will be no anaeorbic bacteria, and if it is too deep, you will have anaerobic areas that will release toxins in the water.

Craig

Link to comment
Share on other sites

Daniel, one sentence particularly caught my eye from your post.

Some people say it also replaces vital nutrients etc, but I have never seen and proof of this.

Have you looked for the evidence and information to back this up or just written it off?

You then go on to say you have plants. Do you fertilise these plants? If not, then you will be losing nutrients from your water and never replacing them. Plants do not live on/process nitrates alone, but also many other trace elements.

It is really too much to go into, but when I have more time later, I will provide many many links, courtesy of a google search.

Link to comment
Share on other sites

btw, I am not suggesting you just use a bucket of water to seed a tank. I said substantial volume. The best would be a whole tank but I have found the third seems to work for me (i.e. new tank with no deaths, fish seem to have no problems and fish seem not to be stressed). I agree, because the bacteria do tend to live in film colonies the best way is to move those colonies whole, such as on filter media in substrate.

The article is circa 1997.

Link to comment
Share on other sites

Guys,

I feel I should clarify a few points that I wrote in my earlier post.

Firstly, my point that most filters reduce nitrates. There is a fine line to this as most filters obviously convert ammonia into nitrite and then into nitrate, hence they obviously produce nitrate which is their main purpose. However, cannister filters are known to actually reduce nitrates to nitrogen gas when the media is allowed to clog up a little or is packed tight with media. (Against this, as CT Thompson suggests, it may also need a clean when it gets too packed with waste, it comes down to trial and error to create these conditions). I have clearly seen this nitrate reduction in the many nitrate tests I have performed on non planted tanks. Reduction of nitrates will occur given the right conditions (basically blocking oxygen supply within the filter). Their is not much chance of doing this with wet dry filters due to the excessive oxygen supply within these systems. However, I have surprisingly also seen this nitrate reducing effect with a few trials on a large HOB filter, also in a non planted tank.

Secondly, iro my point on fine gravel also having a nitrate reducing effect. Whilst I can't confirm this with my own tests, their appears to be quite a bit of evidence out there to back up this point. And almost overwhelming evidence amongst saltwater aquarists.

Thirdly, iro replacing vital nutrients. Well as I said earlier I have not seen any evidence that this is the case. Nor would I ever be too worried about it, as all closed water systems (WC or no WC) need evaporation top ups, and hence would have vital nutrients replaced this way.

The bottom line is a nitrate test kit is relatively cheap, and hobbyists should perform these tests to work out the best routine for their systems. Many people

who do not perform nitrate tests may be water changing way too often.

Link to comment
Share on other sites

Daniel

my point that most filters reduce nitrates. There is a fine line to this as most filters obviously convert ammonia into nitrite and then into nitrate, hence they obviously produce nitrate which is their main purpose. However, cannister filters are known to actually reduce nitrates to nitrogen gas when the media is allowed to clog up a little or is packed tight with media

I take your point here, and there is truth in what you say.

But the time a filter starts to clog, reducing conversion from ammonia to nitrite, and increasing the breaking down of nitrates due to reduced water flow and an increase of aneorobic conditions, in your words, is a “fine line”. The brief time a filter producing a reduction of nitrate, and yet still breaking down enough ammonia, would be a very much on the edge of a fence, way of maintaining a healthy eco system in a tank.

To indicate to people that this a good method of nitrate reduction is not something most people could achieve. What if they leave the filter too long? How can a filter be run in this method 100% of the time (which I realise you are not advocating). How does one know that NOW is the time when the balance between ammonia breakdown and nitrate removal is past its optimum, and know this 100% of the time? If one tried to run a tank like this there would be swings in the amount of ammonia reduced/present, and the same for nitrate. This is not a productive long term solution to maintain an aquarium.

If your filter is at a stage of reducing nitrates, it is also dirty enough for it to be at the stage for your ammonia conversion to be restricted. What is more toxic, ammonia or nitrate? For this reason also, a filter should not be left to get to the stage where one perceives a benefit of nitrate reduction.

Many people who do not perform nitrate tests may be water changing way too often

Water changes are done for more than just removing nitrates. Just because you have a system that removes all nitrates, doesn’t mean you have also removed all the other pollutants that nitrates could be used as a yard stick for. That is, if you have zero nitrates, you still do a water change, because there are other things in the water that you export when changing water.

Secondly, iro my point on fine gravel also having a nitrate reducing effect. Whilst I can't confirm this with my own tests, their appears to be quite a bit of evidence out there to back up this point. And almost overwhelming evidence amongst saltwater aquarists

In regards to evidence of saltwater aquarists and their overwhelming evidence; I can only think you are referring to a plenum. A plenum is set up with highly demanding controls and limitations, with VERY exacting methods of constructions. This cannot be compared to gravel (or what ever substrate) sitting on the bottom of the tank. Yes, you can set up a plenum in a fresh water tank, but you would need to just as demanding in construction methods as a salt water tank.

If you want to reduce nitrate, build a nitrate filter. It is not hard. I constructed another one just two weeks ago. Simply buy a large pipe (I used a 150mm one), close off both ends with end caps (I used a glue-on one end, and a screw-on the other for future access). Add bulk head fittings to both ends to allow water passage from one end to the other, and fill container with SeaChem’s Denitrate. Add pump with slow flow rate (189 LPH / 50 GPH). The water needs to be pre-filtered before entering this chamber, but once matured, this is a permanent way to reduce nitrate. Keep your filter clean and and with a good bed of biological media, you will maximise ammonia breakdown. With a properly set up denitrate filter, you can eliminate you nitrate as well, and both of a permanent, sustainable, balanced long term situation.

But, you will still need to water change.

Craig

Link to comment
Share on other sites

I find that over filtering always works for me. I do roughly a 25% change once a week and clean my filters out once a fortnight. Even though most people say that turning over your tank water 6 times an hour is sufficient; in my last few tanks the minimum I let the tank volume get turned over is 15 times an hour. Some of the guys here might think I'm an idiot for doing it, and that it is overkill, and that very well may be the case. But by the same token I have not lost a single fish, not one, in 5 years. Not to disease, not to aggression, not to jumping ... nothing.

I have only ever kept a couple of tanks at once, so perhaps this 15-20 times an hour aim is simply not economical for those with multiple tanks/breeding setups, which I completely understand. I am not here to profess my way of doing thing is any better than anyone else's, it is however what has worked for me thus far. Aquaria for the most part seems to be about balance and finding your niche, or perhaps more accurately, your routine. If a 50% change once a week and cleaning your filters once in a blue moon is working for you, and has worked for you in the past, then dont let anyone tell you that what you are doing is wrong. I am a relative newbie in aquaria however in my dealings working at LFS' I have found one undeniable truth, and that is that what works for one person may not work for another.

Of course there are things we all agree on. Filtration is good, cichlids are good, this forum is good; these are the "facts" so to speak. There are however a vast majority of points in aquaria, as Im sure there are in any hobby or field, that will forever be contentious and paraphrase Star Wars, as Obi Wan said to Luke, a lot of what we believe is based on point of view.

Whilst this is a long winded and convoluted way of making my point (but hey, thats me), what I am getting at is that trial and error, research, interest and a willingness to learn are the things that will make your fish keeping a success. Not listening to only one side of an argument, not telling people that the way you do things is the one and only correct way (and no I am not aiming that comment at anyone in particular) and certainly not wasting your time trying to convince someone that you are indeed correct when they've already made up their mind that what they believe is absolute truth.

So to address the poor fella that started this thread. Your head is probably spinning right now, wondering what the hell is going on when all you asked (in essence) is whether lots of water changers are good. But to answer your question mate, and I dont mean to sound vague; do what works for you. Keep your fish, watch them. If after you do massive water changes they seem to gasp for air or act weird, cut them (the changes) back. If your plants die with frequent changes, perhaps you should focus on replacing trace elements instead of removing water. Alternatively, if you test your water and your getting ammonia or your fish are looking crook, maybe you need to do regular or larger changes. You'll only get out of this hobby what you put in. But its the finding things out, the excitement of adding new fish and crossing your fingers that you don't lose any, the arranging the tank and watching the fish grow and mature ... that to me is what this is all about. I'm sure you will find your groove, I know I found mine wink.gif

Link to comment
Share on other sites

So to address the poor fella that started this thread. Your head is probably spinning right now, wondering what the hell is going on when all you asked (in essence) is whether lots of water changers are good.

thumb.gif

It was my intention to ask a loaded question. With something such as water changes there is never a straight right or wrong way of doing it.

I believe that all the replys posted on this thread have something to offer everyone who enjoys the benefits of an open mind. smile.gif

As a very very new person to this hobby it is always good to get a wide range of view points.

So thanks to all for the replies. clap.gif

Link to comment
Share on other sites

In the end how often you change your water will depend on your motivation. Your motivation hopefully will be effected by your knowledge on the topic, and the greater you understand the reasons behind a water change, the more able you will be able to make not only a decision, but the best decision there is to be made.

Ultimately, how frequently you change water, and how much you take out should be dictated by your tank size, and stocking level (stocking level = how much food you put in there).

As a rule of thumb, start with 1/3 per week, do less or more based on your knowledge, and your motivation.

You can do a lot more if you set yourself up to do so (pre-prepared water etc.), or less if you have a really small fish load.

Craig

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...