Fish health in relation to no water changes in low tech tanks.

[sciencefiction]

Hi all,
I was just wondering if anyone could share their experience in keeping a tank with no water changes and what effect does it have on fish health?

For example I recently refurbished one of my tanks and it's now planted with emersed tropical house plants(hydroton pebbles in the trickle filter). It also has a few aquarium plants(pictures below), but not many and mostly floating because I am using very low light inside the tank itself. So I only have some floating hydrophila, some hydrocolyte t. and a couple of anubias.

The tank is relatively low stocked for the volume of water(30G). It has 8 kuhli loaches and about 20 red cherry shrimp in it so nutritients provided via fish waste will not be that much.
I do not intend to dose this tank with anything so water changes/lack of may have an effect on it. My tap water is hard, but it's poor in nutritients like NO3 or PO4 so doing a water change possibly means depleting the plants from vital nutritients considering the low stock.

The problem is, I am kind of wired to the thought of doing my 50% weekly water changes on my low tech planted tanks and have been doing so for a long time with very good success. I have never had any algae issues, or BBA outbreaks as suggested by some due to CO2 fluctuations(although my tap water is rich in CO2), so that's not my concern at all. My fish/shrimp have been doing great with such a schedule. But to keep such tanks successful, I always need higher stock levels and lots of food.

This tank however is not going to be stocked with anything more than it already has+whatever amount of shrimp breed in there. So is it safe not to do water changes as long as my nitrate/TDS levels aren't high enough to affect the fish(if they do at all) or what exactly is the reason we do water changes in fish tanks, providing the majority of parameters like TDS, Ph, Kh, Gh, etc.. are not fluctuating rapidly, or rising beyond acceptable levels?

This is the tank in question:

 

[tim]

I do them because I like to 🙂 just change 10% rather than 50 % if your looking for less hassle.

 

[Michael W]

I only do water changes on my low tech tanks when I feel I have time. I have Peace Lilies growing on the HOB filter with loads of floating plants including duckweed, red root floaters and frogbit. The stock consists of 15 Neons, 4 guppies and 4 bronze Cordoras in my 22 gallon.

Some people will argue that in a heavily planted low tech tank all you need to do is to provide enough flow for the plants and they will filter the water for you. I don't find problems with this and my stock seems healthy. If you have a lightly stocked tank with good vegetation there really shouldn't be any problems with no water changes but doing them won't harm.

 

[Ady34]

Personally I would always advocate water changes, even if only small and on a monthly basis.
It's necessary to vacuum detritus, maybe, even in subtly lit aquariums, to give the glass a scrub to remove algae etc at some point and replacing removed water with clean water will only be beneficial.
What about airborne contaminants within our homes. Maybe not a huge issue but long term exposure to air fresheners, sprays, maybe even cigarette smoke without a water change may have a negative effect.
I'm sure there is more at play within our closed systems than the obvious and a water change is a simple way of keeping things sweet.
If your concerned about removing nutrients with a water change then observe the plants, if they show a deficiency adding a very small amount of fertiliser won't break the bank. Your floating plants are a good indicator of nutrient deficiency as they have unlimited access to co2 and receive the most light.....if they fail then most likely nutrient supplementation is necessary.
Cheerio
Ady

 

[sciencefiction]

Thank you all.

I was just wondering, besides possible contaminants, what else is at play when it comes to fish health if let's say the major water stats are stable and within required parameters. What does it mean to put "clean" water?

I don't mind doing water changes, with a python it takes 5 min to do a 50% water change on that tank.
But the tank has shrimp in it, so I am not willing to dose ferts if it can be avoided or reduced to minimum.

With the fear that I'd be sounding like bragging, that tank on the picture has been setup for around 3 years before the rescape, and I only remember cleaning the glass on it once in that period of time. I didn't touch the glass even recently when I rescaped the tank. So are my other 2 low tech tanks. Somehow algae has not been an issue, even when I've had plant deficiencies that I needed to address.

As for detritus, I wonder what happens to it, because again in my other low tech tanks there's nothing to siphon. I just clean the filters when I think of it. However, they do have plants planted in the substrate so that's possibly a factor for success.

I know how it will sound, but in my experience so far, the less I clean and fiddle with the tanks, the better they run, at least the low techs. If the shrimp are multiplying like rabbits in such setups without getting sick or dying, then it probably works to an extent. The only barrier I haven't crossed is not doing weekly large water changes and I don't know if changing the schedule would have detrimental effects on the fish, and positive effect on the plants, or not...

 

[Yo-han]

What about certain organic substances which a filter is not able to deal with? Or lets say copper in the fish food. Without water changes these substances may build up till they become lethal. Things you can't measure...

 

[dw1305]

Hi all,
Nice tank, I agree with the others really, I'm not convinced by the "fluctuating CO2 causes algae" argument, and I think all tanks are better with regular water changes. I usually work on about 10% a day, but it is probably more than you need. Because I use rain-water, I have cleaned, old 6 pint plastic milk cartons for water changes, I draw the water the night before, and then in the morning, assuming it has swimming Daphnia, in it, I change the water 2 x 6 pints for 2' tanks and 1 x 6 pint rainwater + 1 x 6 pint of tank water from the larger tank for a nano, the tank water is partially for thermal reasons. Every few months I measure the Tds to make sure it is in 50 - 70 ppm Tds range. I only keep "jungles", and if plant health is declining, I add fertiliser via the "Duckweed Index".

Tom Barr has been successful with no water changes, so it may depend upon your level of awareness of tank health, but I think some of the problems Diana Walstad suffered with her Rainbow fish were due to her reluctance to change any water.

Have a look at this thread <Low tech - no waterchanges? | UK Aquatic Plant Society>.

cheers Darrel

 

[sciencefiction]

What about certain organic substances which a filter is not able to deal with? Or lets say copper in the fish food. Without water changes these substances may build up till they become lethal. Things you can't measure...

Yes, that's true. I actually don't feed the shrimp tanks food that contains copper.
But what exactly are these organic substances that don't get processed and don't get used up by plants for example?
Is mulm a bad thing?
Can one monitor the dissolved organic build up by measuring the TDS or not?

 

[sciencefiction]

Tom Barr has been successful with no water changes, so it may depend upon your
level of awareness of tank health, but I think some of the problems Diana
Walstad suffered with her Rainbow fish were due to her reluctance to change any
water.

Thanks Darrel. I read about the rainbow fish issue myself. She was dealing with mycobacteriosis from what I read(http://www.atlasbooks.com/marktplc/00388mycoarticle.pdf) Do you think that was caused by bad water quality maybe? I am dreading such a thing. The problem is that I have another tank that I setup similar to a "Diana Walstad" tank, so the question I have relates to both tanks in a way.

Nice tank, I agree with the others really, I'm not convinced by the "fluctuating CO2 causes algae" argument, and I think all tanks are better with regular water changes. I usually work on about 10% a day, but it is probably more than you need.

Thanks. Yes, the "fluctuating CO2" caused by large weekly water changes is no cause for algae for sure, at least on 3 of my tanks. I've done that for a very long time now and haven't been able to cause algae by doing 50% weekly water changes. My tap water Ph is 6.6 and raises up to 7.4 once it outgasses the CO2. If anything, it has a good effect on the tanks.
So it seems I'll stick to water changes, but I'll maybe try smaller ones instead and learn to watch the plants response 🙂

 

[Alastair]

When I originally set up my chocolate puddle tank I went through a phase of rarely changing any water at all and never saw any negative effects on fauna or shrimp. It was heavily planted above and below and I even kept crs too. I added ferts but only at a very low dose and occasionally. I then decided to start doing ten per cent water changes each week purely as the dissolved organics, rotting leaves fish waste etc were causing the tds to rise slowly. My tap tds is 58 but with out water changes during 3 or 4 months just top ups, my tds had risen to nearly 400.

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[sciencefiction]

Thanks Alastair.
Yes, I've noticed the TDS tends to go up, although slowly. I've been skipping water changes on my other tank and that's exactly what happens. But then high TDS is something common for high tech tanks as well, despite the regular water changes. I suppose it's the nutritients added maybe.
It probably matters to the fish what exactly raises the TDS, whether calcium and magnesium, or high nitrAtes for example, or dissolved organics, or other minerals.


Thank you all for your advise.

I think I'll do the same. I'll just keep the TDS at bay with as many water changes are needed and see how often and how large they need to be to make that possible in these tanks.

 

[Alastair]

I do two ten percents a week which holds my tds at 120

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[sciencefiction]

I do two ten percents a week which holds my tds at 120

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Thanks. I'll try that.

 

[Ravenswing]

I doubt if there is The One and Only Aswer to this. Electrical conductivity from tap here is 420-600uS, fertz and water conditioner raises it ca 100uS (fertz with non-EI-method). Since I dont do 100% WCs but 50-60% weekly, the EC in the tank is usually 600-750uS just before WC. If I keep adding fertz and not doing WCs, EC keeps rising and rising, this is what my EC-meter shows me. From day to day. One can wonder what fishes might like this way of "maintenence" after couple of months... The tank was heavily planted with emersed culture. My bows showed signs of stress at 800uS wich was reached within 1,5-2 weeks after WC. Angels and Kongos, for example, show never signs of stress no matter the EC, they must be hard! So, I think, "no-WCs" is not an (good) option for all though I know thre is only handfull of people with similar bad water as we do. Now I have teared that heavily planted tank down, just few plants, lots of bogwood and branches, just root tabs for ferz and EC stays around 600uS (before WC). We are having five different shrimps and they seems to do fine tanks at 400uS, where EC is kept down with tons of bogwood and regularly weekly WCs but Im definetly not sure what would happen to them at 750uS...

 

[dw1305]

Hi all,

Is mulm a bad thing? Can one monitor the dissolved organic build up by measuring the TDS or not?

Yes and no, mulm isn't a bad thing in a low tech tank, a lot of successful keepers and breeders of Apistogramma etc keep very mulmy tanks. The late Bob Marklew (Pleco breeder extraordinaire) had mulmy tanks even for fish like Loricaria simillima: <View topic - Spawning of Loricaria simillima>.

TDS really measures just the ions (because TDS meters measure conductivity, then divide it by 1.8 and call it ppm TDS). Dissolved organic carbon (DOC) doesn't contribute to TDS directly (it doesn't carry and electrical charge), but the processes that produce DOC are also likely to add TDS to the water.

Scientists who work on water quality use chemical oxygen demand (COD) and biochemical oxygen demand (BOD), which takes into account all the abiotic and biotic processes that utilise oxygen, but unfortunately we can't really measure them without a dedicated lab.

TDS/conductivity isn't the parameter that we would really like to measure, but it is about the only parameter where we can dip a meter/test kit in and get an accurate and repeatable reading.

cheers Darrel

 

[dw1305]

Hi all,

She was dealing with mycobacteriosis from what I read. Do you think that was caused by bad water quality maybe?

Yes and no again. I don't think it was caused by poor water quality, and it is apparently fairly common in Rainbow fish (the linked pdf is an interesting read, but may give you nightmares).

The problem I see is that the disease is likely to develop in stressed fish, when their immune system is compromised. I'm reasonably convinced that if she had had fewer fish and regular water changes it wouldn't have manifested in the same way.

cheers Darrel

 

[sciencefiction]

Thanks very much for all your input guys. I'll stick to small water changes.

I had done a water change on the tank 2 weeks ago and the TDS had risen with about 10 ppm since. I did a small one today to get back on track. It's actually hard doing a small water change on a tank like this because I've got to stop the python before it even starts 🙂

I took a video of the kuhli loaches yesterday piling up on an algae wafer if anyone is interested.

 

[Ravenswing]

^ Cool tank, I really like it! Our Kuhlis of four different species have been just fine with our high EC so I wouldnt worry about them.

According to my own experiences, one can ignore TDS/EC and WCs but one can not. It depends on starting point (low/hight right from tap), fertilization and stocking (more fish more waste). I dont see a big role for plants because they need to be fed too, you cant starve them to hunger and melting/struggling plants are another problem aside EC. EI-method, for example, rises EC more or less, usually more. I personally couldnt see plants "handling" EC practically at all. Thou they "eat" salts away, the affect is still very small and as soon salts (=fertz) are eaten, plants are strugling and you need to add more food for them in a way or another. Yes, a perfect balance between plants and plant food load can be found, but you need to observe the growth of plants tightly for not to cause defienciensies.

When it comes to original question about connection between TDS/EC and fish health, there is a connection. Im 100% sure, by what Iv seen in my own tanks that when EC reaches some point, fish start getting sick and start dying. Organic residuals are another strory thou NO3 in all our tanks has always been very low by strong vegetation, 0-5 ppm without adding it . However, that "some point" is different with different fish species. I have evernever heard that someone has kept species known as "sensitive" (=picky about water quality and/or originally from very soft (under 100uS) wates) succesfully for a long time here in my home town, no matter how often they do WCs. It is known that fish do handle salts via their osmoregulation system and that cause stress by producing catecholamine and cortisol hormones. This is what I have found: "...If the stress is persistent and of sufficient intensity, changes in the cellular structure of the gills may occur under the influence of cortisol. In this situation, increased death and turnover rates of branchial epithelial cells leads to accelerated aging of the gills. These degenerating and newlyformed gill cells do not function normally, which further limits the fishs ability to maintain water and ion homeostasis under stressful conditions. Thus, acute stress limits the fishs capacity to osmoregulate, and prolonged periods of extreme stress may result in osmotic shock and death...." Well, my own experience with some less-sensitive species are that one can help them a lot keeping water clean from organic waste. As soon as one stop WCs for some weeks-months, problems start with them. I cant know if it is beacause of high EC or organic compounds but for sure high EC causes stress in fishs body and that might cause other negative things affect fish even more badly. But as stated above, the whole thing depends on many factors and thats why there is no absolutely answer if someone can desist WCs without harassing the fish. Or plants as well. Luckily most people have naturally low EC/TDS and therefore it can be ignored. As far fish seems to do fine, everything is fine. Generally I would be much more conserned about organic waste than EC!

 

[Guest]

I had a low-energy 50 gal planted tank for several years in which water changes were practically non-existent, and while I suppose it's logical that TDS will tend to creep up with continual top-ups I never had any probs with critter health, in fact quite the opposite and my water is very hard to start with.

But then it was a large tank and as we all know dilution is the solution to pollution. Then again it was also very heavily planted. So I guess it all depends on synergism between several factors like bioload, planting density, feeding regime, etc

Anyway, in my experience as a general rule of thumb about 20% - 30% every one to two weeks is fine in most cases. If stock levels are low to moderate water changes will be required even less frequently still, about 50% of the water every 3-6 months, but not necessarily all at once.

 

[roadmaster]

I have for decades changed at least a portion of water from my tank's each week.
Tried to follow Tom Barr's Non CO2 method in the beginning with my low tech,low light tank's(no water changes), but old habit's die hard.
Once I saw that weekly water changes had no adverse effect's with plant's with respect to algae.. I then resumed with my water changes.
I add dry fertz as per Tom's suggestion once a week or two.(Maybe 1/3 EI)
325 litre tank I recently tore down to rid it of trumpet snail's ,had over 100 fish, and water changes each week kept the tank as clean as I want it/like it.
Same tank now,same plant mass,but only about 30 fish (cardinal's,cory's) can go nearly three week's before water begin's to look heavy,,clarity compromised,fishes acting more sluggish.
Plant's performed a little better with increased number of fishes I suspect ,,due to more food being offered and a little more CO2 from fishes as by product of respiration,and a little to a lot more bacterial activity on substrate processing waste.
Am saving $$ for group of Adult Discus,and three or four dozen more cardinal's,and a few more Sterbai corydora's this spring.
Will then reume with weekly 50-60% water changes which have been good to me.