Which parameters do fish care about?

Yo-han

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In (old) books you always read about the importance of pH for your fish. Also the hardness seems to be important and alkalinity, KH, GH and TH are frequently mentioned. Same thing for TDS. I want to know what fish really notice and how. For example, will fish notice (and do they care) the difference between, very soft water, almost no KH/GH but a TDS from 600 from lets say fertilizers. And water with a lot of carbonates, calcium and magnesium but the same 600 TDS. Or keep the KH and GH the same and raise TDS with other ions, will they care? Which is the most important for fish to maintain at there natural levels?
- pH
- KH/alkalinity (I know the difference)
- GH
- TDS
- Anything other?
 

BigTom

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Excellent question and one I'd been considering posing for a while. I think it'll be difficult getting much hard data though and suspect you'll get very different answers here compared to, say, a cichlid or anabantoid forum.

I know people like Tom Barr have no problem keeping and even breeding supposed soft water fishes in full on EI setups. I've (accidentally/ignorantly) kept Parosphromenus in medium-hard water, but they certainly didn't breed. I think you'll need to make the distinction between simply maintaining fish, and having them breed. With Paros, for example, you need very soft water with almost no Ca content for the eggs to hatch, but this is probably partly down to them apparently have incredibly low bacterial resistance. I think a lot of it will be specific to individual species, and to a degree whether they're wild caught or captive bred.

Personally I always try and keep fish in an approximation of their natural waters; it typically isn't difficult to do with a little forethought (ie, picking fish that suit your water, rather than trying to tailor water to your fish, although that needn't be too onerous either) and is one less thing to worry about.
 

dw1305

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Hi all,
I'm not sure there is an answer, if you keep Lake Tanganyika cichlids then pH, alkalinity and dKH are really important, and small changes in pH reflect huge changes in water chemistry.In the Lake Tanganyika case my suspicion would be that conductivity is irrelevant, and you can probably get up to several milli-siemens conductivity without any adverse effects

The real problem then comes when that same person wants to keeps SA cichlids, and you tell them that pH is a moveable feast in soft water, or that you can reduce the pH from pH8 to pH6 in an hour by changing the CO2~HCO3 equilibrium, but this doesn't change the alkalinity and the fish aren't bothered.

The conductivity question has come up a lot on "Apistogramma forums". Have a look a this thread:<ok | Apistogramma.com>.

cheers Darrel
 

Yo-han

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Ok, lets think of it from a different view. Lets say someone bought fish from my lfs (lets say SA, soft water fish), he comes back, they are all dead. Lets assume he treated them like he should. Besides the obvious NO2, what parameters would you test? We always test pH and TDS. I know the tap water around here has these values: KH: 5-12 depending on the city, pH: 7.5 - 8, TDS 250-400, NO3: 1, PO4: 0, no chlorine or anything.
So if pH or TDS is way off I can test for NO3 or KH.
But what are bad values? My EI tank has a TDS of >750 before the water change. This is qualified being too high. KH and NO3 are tested, NO3 is 30-40. No new fish? In a non EI tank I would say yes! If no NO3 is added and you have these values, the water can't be clean. So what would be a good value to determine whether the water is the problem, or the fish weren't healthy in the first place?
 

dw1305

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Hi all,
But what are bad values? My EI tank has a TDS of >750 before the water change. This is qualified being too high. KH and NO3 are tested, NO3 is 30-40. No new fish? In a non EI tank I would say yes! If no NO3 is added and you have these values, the water can't be clean. So what would be a good value to determine whether the water is the problem, or the fish weren't healthy in the first place?
I think you've answered your own question really, TDS can be very high for a number of reasons, and very clean water may have a high TDS (sea water is 53,000 microS). The same with NO3- ions (if we could measure them accurately), there would be a world of difference between adding them as KNO3 and their presence being the "smoking gun" of the biological oxidation of ammonia (NH3).

I think the problem is that there are just too many parameters that we can't measure accurately. I've got access to an analytical lab. but even then I couldn't tell you whether a water sample was "good" or "bad" with any certainty. As an example the UK Environment Agency "Blue book" lists 236 methods for quantifying water quality followed by 83 pages of "parameters and topics" <http://www.environment-agency.gov.uk/static/documents/Research/SCA_Blue_Book_236.pdf>. This has led to most people estimating water quality using the BOD5 method <The Determination of Biological Oxygen Demand> and a biotic index (like BMWP <Origin of the BMWP Scoring System>) which is a really just a form of aquatic organism bioassay.

I'm probably deluding myself but I think I have a pretty good idea of water quality by just looking a the tanks, in my case because I'm not aiming for maximal growth I can use unexpected improvements in plant growth and colour, as well as the more normal parameters, as a visual clue.

If I can't measure a lot of parameters accurately what I can do is use the parameter I can measure, in this case really just electrical conductivity. After that experience has shown me that a large plant mass, including some plants with access to aerial CO2, a high gas exchange surface: water volume ratio, low bioload and regular water changes (with good quality water) are a recipe for a stable and resilient aquarium. It is a KISS solution.

cheers Darrel
 

Yo-han

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And which parameters do fish care for to be stable? By doing water changes in an EI tank you reduce TDS almost by half in a few minutes, no problems... I remember clive once wrote that you can just add EI for a week at once if you like. So raising TDS a few 100 in a few seconds is fine as well. How about KH? I always use the same KH water to do a water change, but the TDS is lower. What if I use about the same TDS but with a way lower/higher KH, do fish care? Dropping pH 1 point with CO2 in an hour is no problem, what about when I do it with acid in a few sec/min?

And on a side note, do plants care if the KH drops a few degree?
 

ceg4048

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Questions like these are always out-of-context because it's assumed that the nature of a fish or plants response is dependent on the absolute value of that parameter, when in fact, it's usually dependent on the phenomenon in the water that is causing the parameter value to change.

As Darrel mentions, dirt and pollution in the tank will always cause a rise in TDS. Pollution is bad for fish and plants, so if there is a TDS instability due to increased pollution, then of course this is bad. If the TDS increase or instability is due to the addition of nutrients, for example, then this is not a big deal because nutrient addition does no harm.

Adding food to the tank causes a TDS rise. Is this good or bad? Food is required by the fish, so there must be some good, but the pollution and Oxygen loss that results is bad. So is the good more important than the bad? If so, then by how much? If we focus on the good/bad relationship of all components we add to the tank we will see that everything is a compromise, because all components have some degree of good and bad. So the answer to the question for this component is that we must manage the amount of food input, and concurrently remove the pollution caused by the food addition. So in this sense it may not really matter that much what the actual TDS number is, but that the component of the TDS that is due to food pollution is minimized, is a much more important approach to fish keeping than blindly following some arbitrary number, because fish are killed by pollution, not by some arbitrary TDS number.

It's exactly the same story with pH. The pH Cultists will swear by some bogus chart showing what minimum and maximum pH values are necessary for some particular fish, yet there are plenty of successful hobbyists out there who routinely break those rules, while concurrently, the Cultists continue to experience failure while they vainly attempt to keep pH constant. If you add CO2 to a tank the pH will fall. When the gas is turned off at night the pH will rise. CO2 is toxic, so if you add too much you will annihilate the fish, but the lethality will be cause by the CO2 ingestion, not by the pH being too low. Many people foolishly attempt to maintain the mythical pH stability by actually adding toxic chemicals to the tank such as "pH Down". These acid buffer products are extremely toxic. Normally they are composed of some strong acids such as phosphoric or Nitric Acid. So the hobbyist dumps loads of this stuff into the tank, which only manages to drop the pH for a short time, because the acids combine with other compounds in the tank over time and are somewhat neutralized. But the toxicity is not neutralized. The pH rises, and the hobbyists responds by adding more toxic acid. Sometimes the hobbyist perceives that the opposite "problem" is in the tank. The pH seems too low, so they add "pH Up" which often is just a bicarbonate product, and is sometimes Sodium bicarbonate. Sodium is toxic to freshwater fish and plants. It's a lot more toxic that just leaving the pH at a low value.

So really, if you are asking the question of what parameter matters, then you have to look deeper into what causes the parameters to rise or fall. That is where your answers are, not in absolute values or in absolute stability. If your KH is high because there is a load of Sodium bicarbonate in the tank then you need to lower the level of toxic Sodium. It won't matter about the bicarbonate part because that's not the part that is dangerous.

It's more important to know what the values in the tank are when the tank is healthy. The equilibrium numerical values are not really important. They are more important to understand as a baseline set of values, so that when they change you can then analyze the tank to determine the causes. If the cause is determined to be innocuous then you don't have to worry about what the particular number is or what the stability is.

Some people use substrates or hardscape which contains lime. They add CO2, which produces a weak acid, and this dissolves the lime, so TDS, GH, pH and KH all increase over time. The fish don't really care too much, except that there is still the problem of organic pollution, caused by the fish and plants themselves, which, as I mentioned, also increases the TDS. But what happens is that the hobbyists focuses on the fact that some agent is causing the GH, TDS and PH to all rise, when they really ought to be paying attention to the component of TDS rise caused by the fish and plants themselves. All they have to do is to change the water, keep the tank clean and not worry about anything else, but The Matrix teaches us to spend enormous amounts of energy trying to fix a problem that doesn't actually exist.

Cheers,
 

Yo-han

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Thanks Darrel and Clive, this is all makes sense! The reason I ask is that the lfs I work provides a week warranty on fishes. But in order to receive new fish we want to test the water to see whether that is a cause of death. Off course, NO2 needs to be zero, otherwise no new fish. But what other parameters can you test to see whether the water is good. Tap water around here has a TDS of around 250, so when non EI people come in with a TDS of over 500 it is most likely pollution and this means no new fish. But when the same person uses EI, TDS can easily be 750-800 at the end of the week, but this isn't bad for the fish obvious. Same thing for NO3 or PO4. Too high, no new fish! (This way anyone using fertilizers is excluded and this didn't seem right to me.) But I think there is no simple way of telling without asking some questions except for NO2...
 

roadmaster

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Well if their tank's aren't planted ,but Nitrate level's exceed 40 ppm, then this is a sign of poor maint,too much food,poop, too many fish,not enough water changes or water changes not large enough to export the waste. = more manageable nitrAte reading's.
Me think's there is big difference between nitrate reading's as result of dosing minerals KNO3, and nitrate reading's as result of dissolved organic's.
 

ceg4048

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The reason I ask is that the lfs I work provides a week warranty on fishes. But in order to receive new fish we want to test the water to see whether that is a cause of death. Off course, NO2 needs to be zero, otherwise no new fish. But what other parameters can you test to see whether the water is good.
Really Johan, the only way to know what killed a fish is to do an autopsy, but since few people have the tools or skills to perform an autopsy we try to use the circumstantial evidence which is unreliable. On top of that is the fact that no Nitrogen test kit has any kind of credibility, and on top of that people still believe that NO3 and PO4 are toxic. The whole system is built on a house of cards. It's the neural, interactive simulation we call The Matrix.

Probably Darrel's measurement of Biochemical Oxygen Demand (B.O.D) would be the most appropriate indicator of organic pollution, since this technique is used in waste water treatment, but good luck with that.

Cheers,
 

Yo-han

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Haha, Salifert does have a new organics test. Don't know how it tests organics and or it is any good but I think it is all about Q&A otherwise...
 

dw1305

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Hi all,
Probably Darrel's measurement of Biochemical Oxygen Demand (B.O.D) would be the most appropriate indicator of organic pollution, since this technique is used in waste water treatment, but good luck with that.
Haha, Salifert does have a new organics test. Don't know how it tests organics and or it is any good but I think it is all about Q&A otherwise...
I'd be a bit dubious about the test, Biochemical Oxygen Demand (BOD) is the only measure that takes into account both the biological and chemical oxygen loading in water, but unfortunately it is out of reach even for most labs.

Because of the demands of time and space involved with BOD testing, a lot of continuous monitoring for organic pollution is now done by "FLUORESCENCE ANALYSIS", this uses tryptophan as the marker compound. I spoke to a couple of companies about a quote for a monitoring SONDE to go into our campus water course, but unfortaunately the fluorescence monitor is an expensive one.

We're still in negotiations about a MANTA2 sonde <Multiparameter Water Quality Sondes & CTD s>, the sensors we'd like, and the ones we can afford.

Details here: <Tryptophan-like fluorescence (TLF) - an early sign of organic pollution>.

cheers Darrel
 

roadmaster

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My fish keeping began with large South American Cichlid's in number's to minimize Aggression,Territorial issues.
Most who have kept them for any length of time, will tell you that lower nitrogen level's = healthier fish.
Large frequent water changes,careful feeding,reg maint, help prevent process (ammonia to nitrites,to nitrates,) that render's the nitrate reading's on average hobbyist test kit's from harming the fish over the long haul.
Is simple to prevent dirty enviornment.
Some can argue as to what constitutes excess,or harmful level's of Nitrogen if they like, but is much easier to prevent excess level's than to debate in my view.
 

dw1305

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Hi all,
Most who have kept them for any length of time, will tell you that lower nitrogen level's = healthier fish. Large frequent water changes,careful feeding,reg maint, help prevent process (ammonia to nitrites,to nitrates,) that render's the nitrate reading's on average hobbyist test kit's from harming the fish over the long haul. Is simple to prevent dirty enviornment. Some can argue as to what constitutes excess,or harmful level's of Nitrogen if they like, but is much easier to prevent excess level's than to debate in my view.
I agree with this, but with some proviso's.

The situation is different between un-planted tanks, (where "the only solution to pollution is dilution"), and planted tanks where levels of NO3 will decline over time, rather than increase. I know I've said it plenty of times before, but plant / microbe systems are much more efficientat biological filtration than microbe alone systems, something like x10 more efficient. Plants take up NH3, NO2 and NO3, provide extra sites for microbial nitrification and are net oxygen producers, it is a "win-win-win" situation.

The other proviso's are the readings on any nitrate test kit are so variable you can't really draw any conclusions from them and even if we could it is the source of the NO3 that is relevant.

Clive can have high NO3 levels in his tanks why being fairly OCD about cleanliness, because he is adding a lot of inorganic fertilisers via EI.

High nitrate levels only indicate polluted water if they are the "smoking gun" of high NO2 and NH3 levels, not if they have been added via KNO3 etc.

cheers Darrel
 

roadmaster

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Yes,I agree. It is the process that produces the Nitrate reading's.
KNO3 is inorganic mineral salt, which does no harm that I can see after a couple year's now at varying levels in my tank's..
Just thinking, that many folk's don't run planted tank's here ,and water samples with high No3 brought to be tested at store for replacement of fishes,,would indicate poor enviornment IMHO.
 

Yo-han

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And which parameters do fish care for to be stable? When dosing EI, and doing a water change TDS drops quite a lot. Do fish notice this? And do fish care/notice it when the same drop in TDS is not from inorganic salts but from a lower KH/GH?

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ceg4048

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Johan, what fish notice most about a water change is that they can breathe more easily because organic toxins have been removed from the water column and bacteria are not stealing Oxygen from the water column in order to break down and to detoxify the pollution.

The Matrix teaches us to "keep my parameters the same", but the problem is that the one parameter that counts the most is largely ignored. Of all the remaining parameters, KH is probably the most significant because it is involved in osmotic mechanisms. Again, however, there is a wide tolerance among fauna and it's really not something to micromanage. Like pH, KH and alkalinity are extremely complicated and so adhering to specific arbitrary numbers hardly adds value.

As we discussed before, solutes that dissolve in the water column, including liquids, raises the TDS. So we can ignore the TDS increase due to EI salts, but we should not ignore the TDS increase that results from pollution, because pollution kills by robbing Oxygen, not by it's microsiemen value.

Cheers,
 

wijnands

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Managing, or micro managing even of the conductivity does play a role if you want to breed some fish.
 

ceg4048

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Yes, I agree, but generally we are not focused on breeding, which is a specialist endeavor. We're talking about maximizing the health of the tank inhabitants by focusing on gas exchange in both plants and animals. Even if we extend the argument to breeding, then control of conductivity alone will not be consistently the only parameter to worry about. One still needs to have clean water, free of excessive levels of organic waste in order for the fish to breed and to raise healthy fry.

Cheers,
 

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