Doing water changes

[Mucky_Waters]

If you have ever been seriously into aquarium keeping you'll know that water changes are very beneficial for the quality of your water and health of your fish. However with ponds things get a little different. First of all, as Addy touched on, unlike most aquariums ponds are outside and can get natural water changes from the weather phenomena called rain. In some areas of the world this can go a long way to taking care of your water changes, but in drier regions the rain they get might not even be enough replace the water loss through evaporation. Which is very true where I live. Of course just replacing water that evaporates is not sufficient to constitute a water change. As water evaporates essentially only pure H2O evaporates and leaves behind all the minerals, calcium and impurities that came with the original water. If this goes on long enough your pond water can get very hard. Evaporation also leaves behind all the waste products produce by the fish and decomposing vegetation including ammonia. nitrites and nitrates. Also fish produce pheromones that they use to communicate with each other. In the wild they use these pheromones as a way of finding or avoiding each other (for instance in mating), but in the confines of a heavily stocked pond a concentrated pheromone build up can have a very detrimental effect on the fish.
So turning over water (water changes) is a good thing, and helps simulate their natural environment, however as Jordan brought up, if done improperly it can stress fish as well. That's why I advocate the drip water changes system as it is the safest and easiest way to change your water, with zero stress on the fish and no need for dechlorinating chemicals.

 

[addy1]

Our water is so soft, even with just adding water I need to bring the hardness up. In Arizona, our water was like a rock.

 

[bettasngoldfish]

Does your pond have a bottom drain Like our own or @bettasngoldfish ?
Our own pond has four huge filters from its life as a QT pond the first is a vortex where all the detrius from the pond ends up .
This I clear on a regular basis removing about 40% water or until the water from the bottom drain runs clear again.
We own a water filter prefilter which removes cholorine/chloromines prior to their entry into the pond making it safe for our koi :-

http://www.vyair.com/scripts/prodView.asp?idproduct=67

Then all we do is trickle the water back into the pond at our lesure .


Dave

I have a bottom drain in my filter for ease of cleaning not my pond

 

[Lisak1]

I forgot about the bottom drain - a BD is definitely a feature in a dedicated koi pond!

Here's another hint - if you are wondering if you have a dedicated koi pond, then it's a sure bet you don't.

 

[cas]

Some questionable information there also.

Anything specific Meyer?

 

[Lisak1]

Very good information @Mucky_Waters . I repeat it often, but one way we manage our water quality is LOW FISH LOAD. People often want to know "what's the maximum number of fish I can have in my pond". Take that number and cut it in half - your fish will thank you. I think all creatures hate to be crowded - I know I do! - so I like to give our fish lots of room to grow. Less fish=less food=less waste. Not hard to see how that is better for your fish.

 

[Fishfinder]

Yes, that makes sense, Lisak1. In that case, it is not a dedicated pond.

The only other plant that's in the pond is parrot feather. It does great. In past years, the koi have not gobbled up the water lettuce so much, but maybe it taste better this year. They are well fed. That's not the issue.

Dave54, we don't have a drain.

I can never remember the number of gallons in the pond, but it's about 7 feet long, 5 wide and about 4 deep. It seems plenty big for 6 koi and a big catfish. I have no desire to add more fish.

Here's a look at some of the plants

I know the parrot feather is meant to be tucked in corners, and it's doing well - there are four bunches - but what lettuce there is likes the corners too. Maybe the increased water flow from the air stones encourages that. I don't know, but I like the air stones. The fish don't seem adverse to them. It's interesting how they lined up, almost as if they were posing.

 

[Meyer Jordan]

Anything specific Meyer?

For starters, the very first paragraph under Water Changes states-
"Water changes are an important part of koi pond management, especially when ammonia or nitrites are polluting your pond. One reason for that bothersome chemical build-up is evaporation. When water evaporates from a closed system (your koi pond) it leaves behind most all of the pollutants. Sure, the beneficial bacteria in your pond are busy doing their job, processing those obnoxious chemicals (the nitrogen-cycle), but sometimes the good bacteria can’t keep up, so partial water changes give them a hand in keeping the peace."
If Ammonia and Nitrite are 'polluting' your pond, you obviously have a problem with the absence of adequately sized bio-filtration. If your 'good bacteria can't keep up', again, your pond does not have properly sized bio-filtration. On the other hand, if you do not, and you shouldn't, have a problem with Ammonia or Nitrite, then what 'pollutants' are we having a problem with?

Secondly, the author brings up the subject of growth inhibiting pheromones. The existence of such a compound was postulated some years ago to explain why fish in the same body of water exhibited different growth rates, especially in crowded conditions. This has been examined several times since in various other scientific research. The result has always been that-
1) This growth retarding phenomenon does not occur in all overstocked, crowded bodies of water, and
2) Although postulated, such a growth inhibiting pheromone has yet to be isolated. All other fish pheromones have been isolated and chemically identified, sex, predator response just being two, but no attempt to isolate a growth inhibiting pheromone has been successful. So the existence of such a compound remains only postulated.
And additionally, if such a compound did exist, intensive aquaculture (fish farming) would be an utter failure financially. We all know that that is not the case. Farm raised fish are generally all of uniform size when harvested.

 

[cas]

such a growth inhibiting pheromone has yet to be isolated

Thanks Meyer. I understand about the first item. The second item was new to me and I am glad that you provided more information about it. So hard to know what to believe.

 

[Tula]

Yesterday I went on a pond tour with a local koi club. These ponds were all dedicated koi ponds and were stunning! They ranged in size from 10,000 - 18,000 gallons, with massive filtration, pumps, double bottom drains and depths ranging from 5.5 - 7.5 feet! The fish were also massive and gorgeous Wow, it was almost overwhelming to take it all in and I'm sure the associated costs are staggering as well!

One house was for sale and the owner said the feed back he's been receiving is not positive about the pond. It seems most folks don't want that kind of maintenance for a pond. I asked him what he'll do and he said he may have to shut it done and temporarily house his fish with fellow club members, till he's settled and had a new pond.

Another pond owners does an almost 100 % water change per week, just by flushing one of he four massive filters per week and flushing her two huge vortex chambers daily.

 

[Mucky_Waters]

On the other hand, if you do not, and you shouldn't, have a problem with Ammonia or Nitrite, then what 'pollutants' are we having a problem with?

First on that list would be Nitrates (the end by product of the nitrogen cycle) which will eventually accumulate in every pond or aquarium. Although nowhere as harmful as ammonia or nitrite, nitrate in concentrations higher than 30ppm nitrate can cause an inhibition of growth and development, cause nervous system damage and degradation (through the inhibition of vitamin B12 uptake, a crucial part of proper nervous system function), and cause general overall stress for aquatic animals.
Beyond the build up of nitrates what other pollutants might build up in your pond really depends on what's in your water source to begin with, and to a lesser degree what pollutants might getting into your pond from an outside source.

And additionally, if such a compound did exist, intensive aquaculture (fish farming) would be an utter failure financially. We all know that that is not the case. Farm raised fish are generally all of uniform size when harvested.

I'm no expert in aquaculture, but from what I understand water changes are common practice in the fish farming industry in closed system ponds. Of course fish raised for food are generally bred and raise for fast growth and harvesting, and the majority of them are harvested before they reach full maturity and start producing their reproductive pheromones. This is a little different then hobby fish keeping where people tend to keep their fish for years, well beyond their age of reproductive maturity.

 

[Meyer Jordan]

The body of literature available on the subject of Nitrate toxicity unanimously agree that at high levels Nitrate can be toxic. The term 'high' is relative and really does not relay any significant information. At what level (mg/L) is Nitrate 'high'.
It is also important to understand that Nitrate toxicity is very specie specific. The lethal level for the most sensitive aquatic organism is 0.10 mg/L. For carp, it is considerably much higher.
For aquarium-
"Nitrate is the end product of nitrification. It is not terribly toxic to fish and can
safely build up in tanks to 50 mg/L or more."
http://web.utk.edu/~rstrange/wfs556/html-content/05-ammonia.html
For garden ponds-
"Nitrate, the end product of the nitrogen cycle, is considered to be harmless to fish in natural systems and ponds as it is used as a fertilizer by plants, including phytoplankton. In closed systems with little or no water exchange, however, nitrate will accumulate and may be harmful if higher than 250 mg/L."
Ammonia in Aquatic Systems
Ruth Francis-Floyd, Craig Watson, Denise Petty, and Deborah B. Pouder
University of Florida IFAS Extension EDIS
As I have stated many times. Nitrate levels are likely to be an issue only in dedicated Koi ponds where no avenues of plant assimilation exist.
If, indeed, levels higher than 30 mg/L begin to cause physiological changes. (I would like to see the link(s) to these research documents), I would tend to think that algae blooms that would be certain to occur before this 30 mg/L level is reached would elicit some form of remedial action.

In aquaculture, RAS (recirculating aquaculture system) is rapidly becoming the standard for land-based aquaculture. These systems require no water changes.
The recommended upper limits of Nitrate levels in RAS for certain fish species are 75 mg/L for trout, 500 mg/L for Tilapia, and >1000 mg/l for cyprinids.
Your reference to reproductive issues is interesting, do you have the link(s) to this research, I would like to read it.

 

[Mucky_Waters]

I don't generally bookmark many links, I just try to go by what I've learned remember over the years and use my understand of things to postulate my views. I'm certainly not always 100% correct, and when somebody shows me where my understanding may be flawed I try to take it into consideration and occasionally change my views. But there is plenty of support and articles out there for doing routine water changes if you want to Google it. One of the problem with posting links anyway is you can pretty much always find something out there to support a particular point of view, and if not you can just interpret what you are reading in a way that support that view. Take your links for example. Your quote from your first link "Nitrate is the end product of nitrification. It is not terribly toxic to fish and can safely build up in tanks to 50 mg/L or more.", but you neglected to quote the sentence that immediately follows that sentence, which says "The nitrate assay is sometimes used to signal the need to conduct a partial water change". So the very link you posted to support your claim that water changes are unnecessary mentions using high nitrate levels as an indicator of when you need to do a water change, thus supporting my initial claim.
Your next quote "Nitrate, the end product of the nitrogen cycle, is considered to be harmless to fish in natural systems and ponds as it is used as a fertilizer by plants, including phytoplankton. In closed systems with little or no water exchange, however, nitrate will accumulate and may be harmful if higher than 250 mg/L." I believe here the ponds they are referring to are natural pond with open systems, since backyard ponds are considered closed systems. So it looks like that link supports my claim again, that water changes are a good idea in closed system ponds, like most of us have.
I think we both agree that there is evidence that nitrates can be harmful to fish in high enough concentrations, but what may be in dispute is how high these concentrations need to be, and which type of fish may be the most vulnerable and when, etc... I'm sure things like PH, water temperature, oxygen levels, age and type of fish are all factors, and any findings from any studies could be disputed because there are so many variables. It's like trying to determine exactly how many cigarettes you can smoke before they effect your health. There is no correct answer except to say that you should avoid smoking and second hand smoke the best you can, and the same answer applies to nitrate levels for fish in your pond. Here is a link with references, though not specific to ponds or koi it talks about how many variables there regarding Nitrates and fish. http://www.oscarfish.com/article-home/water/79-is-nitrate-toxic-a-study-of-nitrate-toxicity.html
Of course nitrates are only one compound that can accumulate in a closed system pond, and with regard to fish reproductive issues and pheromone build up I don't have any particular links on hand, but if you reason on it it's not hard to conclude that there could logically be an issue. Almost all creatures release some sort of pheromones, especially in regard to mating. However most creatures are not normally confined within a closed system, and when it comes to spring spawn imagine what it must be like in a well stocked small pond with so many fish releasing there pheromones without an open flowing system to disperse and dilute them. It's no wonder that you'll often find fish hiding or dying from all the chasing and activities that go on in a pond during spawn. Stress levels must be through the roof. However you could easily ease their stress level by just doing more routine water changes during this stressful period, possibly extending or even saving the lives of some of the fish.

 

[Meyer Jordan]

Well said, Randy.
In my first link that you quoted, it specifically states that the level of concern is 50 mg/L. (I will get back to this later)
In the second link that you quote, it specifically states-"In closed systems with little or no water exchange, however, nitrate will accumulate and may be harmful if higher than 250 mg/L." I take this to include garden ponds which, as you say, are closed systems.
The oscar fish link that you posted is interesting in the fact that at the end of the article the author supplies a link to the opposing view.
As has been said, Nitrate toxicity levels are specie specific. While information concerning Oscars, flathead minnows, trout or other specie may be interesting is is hardly applicable to the typical garden pond that houses Goldfish and/or Carp/Koi. These are the two specie that I have focused on. It has been established that Nitrate is toxic to Carp/Koi at levels >1000 mg/L Goldfish levels, for whatever reason, have not been established, but knowing the durable nature of their physiology and their close relation to Carp/Koi, It can likely be safely assumed that they are at least as tolerant of Nitrate as Carp/Koi.
I would find it interesting to see exactly how many pond owners that test their ponds discover a Nitrate level over 50 mg/L or even 20 mg/L without having experienced a problem with algae growth.
One also has to be careful if using water changes to reduce Nitrate level. A sharp reduction in Nitrate level can have a profound negative effect on fish, much as a rapid change in any other pond parameter.
Although I have seen many, many references to performing water changes after a spawn, I have seen no mention of performing water changes during a spawn to reduce pheromone density.