Volume/Frquency of Partial Water Changes

[AbbeysDad]

In another forum far, far away a fellow indicated he started his planted tank 9 months ago and has never done a water change, just topped with distilled water. He routinely doses with ferts.
Another fellow said he started out doing regular water changes, but thought it was a hassle so he doesn't do them anymore. Someone else is using the EI (Estimative Index) fert method and does 50% WWC.

So what is your volume and frequency for partial water changes for what size tank and is it fish only or planted?

 

[NickAu]

I do 50% once a week, my tanks are planted.

 

[Mrscmurray]

I do 40%Ish in my tropical tank once a week and 50% once a week for the goldfish tank.

I'd love to know how they clean anything without a water change/gravel hoover session! never mind the nitrates....

 

[NickAu]

I'd love to know how they clean anything without a water change/gravel hoover

I have not vacuumed the gravel in my 2 foot heavily planted tank with lots of floating plants in over a year, and my ammonia and nitrite are zero and my nitrates are always under 5.


Live stock
1 Cranky Betta
2 Assassin snails
A bunch of shrimp, They breed faster than pest snails
A bunch of Malaysian Trumpet Snails

 

[julielynn47]

I do a 50% once a week at least and sometimes twice. This is my 55 gallon and it is planted.

 

[Byron]

I do at least 50% of the tank volume, but it is usually (read, always ) 60-70% in actuality. This is the regular WC, once every week without fail. All 8 tanks are planted, some fairly heavily, and all have a good cover of floating plants.

The science is pretty factual, but many will ignore fact for whatever reason and foolishly believe they don't need water changes.

Byron.

 

[Mrscmurray]

Live stock
1 Cranky Betta
2 Assassin snails
A bunch of shrimp, They breed faster than pest snails
A bunch of Malaysian Trumpet Snails

Good point about the shrimp! Live in clean up crew. I'm planning on adding some to the tropical but haven't gotten around to it yet. I do have a handful of mts though who occasionally poke their heads out of the sand

 

[luca1980]

50% every week for all of my tanks (mbunas, tropical community and axolotls). My axies and community tanks are planted, the mbunas just have a hardscape.

 

[StevenF]

In another forum far, far away a fellow indicated he started his planted tank 9 months ago and has never done a water change, just topped with distilled water. He routinely doses with ferts.

I'd love to know how they clean anything without a water change/gravel hoover session! never mind the nitrates....

Keep in mind two things:

1. distilled water is very pure (no minerals).
2. Plants will extract nutrients (minerals and salts) from the water.

So in theory if everything you add is absorbed by the plants the water should stay clear. The plants would remove the nitrates and keeping the water clean. The oceans on earth are an excellent example. Distilled water is added regularly added (rain) and mineral concentrations are constant. Where we add food to our aquarium. Food naturally grows in the oceans.

However there are two issues. different plants have different nutrient requirements. Also fertilizers are not tailored to specific plants. Also fish food will also add nutrients to the water. So overall if you don't cycle water some nutrients will will build up while others will get scarce.

This could eventually cause the water to get hard, trigger algae issues and other problems. However it could easily take months for these issue occurs.

So for aquariums cycling water is necessary to keep mineral levels relatively constant. Most people do this once a week at between 30 and 50% of the tank volume. In my opinion less than 30% is probably not enough to maintain constant mineral levels. While a water change of more than 50% will not be much better than a 50%.

 

[AbbeysDad]

So what is your volume and frequency for partial water changes for what size tank and is it fish only or planted?

 

[Gruntle]

I do 50% at least fortnightly (and fairly often it's weekly) on all three of my tanks (20l, 130l and 200l). All are planted, nitrates are never above 40ppm.

It's not just the nitrates, fish give off hormones that aren't tested for in your regular fishkeeping enthusiast kit. A water change removes/dilutes these and other non-tested chemicals in the water.

 

[Byron]

Now that we are getting into the specific need (some would say reason, I prefer need) for water changes I would like to mention a couple things.

First, nitrates. These are not as harmless as many seem to still believe. They are toxic, though less immediately so than ammonia or nitrite. They should be as low as possible, and reliable sources are now recommending 20 ppm as the maximum. Some fish do have problems at this level, and many more higher. The only way to really deal with nitrates is to do large water changes and every week minimum. One could keep them low by under-stocking fish, and live plants. But most of us keep far too many fish in an aquarium to rely on plants alone, hence the need for water changes. And waiting until you see nitrates rise to do the WC is waiting too late, the detrimental effect of nitrate has already begun on the fish. Remember, nitrates in natural habitat waters of our aquarium fish are so low they usually cannot be detected. That is a far cry from even 20 ppm.

As for the volume of each water change, this does indeed make a big difference. Larger volume changes once a week are more effective and more beneficial than smaller volume changes more often. Example, a once weekly water change of 70% will be much more beneficial and effective than a change of 10% every day. The volume may be the same in the end--10% for seven days would seem to be 70% after the week--but this is not how it works. The aim of a water change is to remove as much "pollution" as possible. The more you remove at once, the better. Remember that pollution is continually accumulating, minute by minute, hour by hour, day by day. I won't get into the maths, but it should be obvious that pollution is going to accumulate faster during the week than you could possibly keep up with using low-volume water changes.

As for these "pollutants," some have already been mentioned. Nitrogenous compounds (nitrate, dissolved organic compounds), pheromones and allomones released by all fish (which no filtration can remove, only a water change), and restoring minerals. But there is more. Fish continually take in water via osmosis through their cells. This gets filtered through the kidneys, and the "waste water" is released. This urine is devoid of almost everything. Freshwater fish retain minerals from the water (the amount can vary with species), and ammonia is released through the gills not urine as in land animals. A single tetra like a neon can produce urine in an amount equal to 30% of its body mass every single day. Think of what this means over time. All the water in the aquarium is being drawn into the fish, "processed," then released back into the aquarium. In due course, the fish are literally swimming in urine which is devoid of anything beneficial.

Live plants can offset this, but minimally. One source suggested that six black neon tetra in a planted 55g tank could function fine without water changes or supplements. Beyond this, it is a continuing decreasing of water quality.

Byron.

 

[AbbeysDad]

I'm on a slightly different path than many...

Diana Walstad ('The Ecology of the Planted Aquarium') took a somewhat natural approach with 1" of organic soil, capped with 1" of fine gravel, heavily planted, lightly stocked, with good water flow but little filtration and no water changes...and the plants grew and the fish thrived. (she felt water changes just removed the nutrients the plants could use.)

But I think she got a couple of things slightly wrong - 1) I don't think there's much value in 1" of washed out soil as it becomes inert very quickly and; 2) Nature constantly refreshes fresh water with rain and runoff.

I'm calling what I'm trying as a 'Nearly Natural Habitat' for my fish.
In my low tech 60g, I'm using about 4" of pure undisturbed silica (pool filter) sand. The tank is heavily planted and fully stocked (currently have 8 small fish [3 angels, 2 cory's, 2 balloon molly's, 1 swordtail, and some 30 {unplanned} fry !! I'm growing out]). I did initially use Seachem root tabs and ferts to get the plants growing. The substrate has a lot of Malaysian Trumpet Snails. I'm feeding high quality Omega One foods.
I'm doing a modest approx. 20%-25% weekly water change in order to freshen the water, replace minerals, as well as preserve and maintain the organic nutrients to feed the plants that purify the water. I will only add chemical additives (ferts) as/if absolutely necessary. I'll adjust both the water change volume and/or the addition of ferts as necessary to maintain a healthy balance...with the objective of being as nearly natural as possible with little/no chemical additives.

My friend Byron suggests that there are far more pollutants generated (pheromones, urine, waste...) than the plants can handle.

I suggest that there is an incredible bio-engine in the substrate and filters of the established tank (way beyond nitrosomonas and nitrospira) that decompose these organics into plant usable nutrients and relatively harmless base elements that the modest WWC will remove.
I believe that this is how nature does it.

In the fish only tank, I feel Byron's 50-75% WWC is spot on.

But maybe I'm all wet <almost punny> and you can't have a [nearly] natural planted aquarium ecosystem without massive water changes and dosing with chemical additives to feed the plants... but I'm going to see if I can...it's only been 6 months, but it looks promising so far.

 

[Byron]

Before I get to the issues, for the benefit of other members I will mention that Michael (AbbeysDad) and I have been discussing this matter in depth for some time, and continue, as we have a couple of unique issues that we are working through. So there may be some gaps here that we have privately filled in. We've known each other for some time from another forum.

My friend Byron suggests that there are far more pollutants generated (pheromones, urine, waste...) than the plants can handle.

I suggest that there is an incredible bio-engine in the substrate and filters of the established tank (way beyond nitrosomonas and nitrospira) that decompose these organics into plant usable nutrients and relatively harmless base elements that the modest WWC will remove.
I believe that this is how nature does it.

This is where things fall apart. It is absolutely impossible to fully recreate nature in a closed aquarium--by which I mean relying completely on "nature" to function as it does in the habitat. We use nature's methods (the naturally-occurring bacteria and so forth) but the ratio of fish to water is so incredibly different from any natural habitat, and there are the various natural processes that we cannot recreate naturally or artificially without water changes.

The "over-population" compared to natural habitats is so great it cannot possibly work. There is a limit to all of nature's methods. As an aside, the environment is able to "handle" short-term problems, such as CO2 emissions, but when these are maintained at such increasing levels for as long as has been the case, nature begins to break down, which is exactly what is happening today. Many believe we have already reached the point of no return. But the point is, that there is always that point, after which the natural system cannot function effectively and it slowly weakens and literally falls apart.

The more fish in the tank, the greater the organics, obviously. Plants cannot hope to handle a fraction of this. And while the various bacteria do process the organics in various ways, the end product remains in the aquarium because the natural means of removing it is missing--and it is this part that the water change replaces. Consider that in the habitat the fish do not live in the exact same water for more than a second. The water they pull in through their gills is never the same water. You simply cannot achieve anywhere close to this in a closed aquarium unless you somehow have the water entering and leaving the aquarium 24/7 so it is always "new" or fresh water. Which brings me to the last paragraph.

But maybe I'm all wet <almost punny> and you can't have a [nearly] natural planted aquarium ecosystem without massive water changes and dosing with chemical additives to feed the plants... but I'm going to see if I can...it's only been 6 months, but it looks promising so far.

The massive dosing of chemical additives is not really necessary...adding some or perhaps all nutrients (in non-chemical forms, just to be clear, using natural nutrients) may or may not be necessary. The mineral content of the initial water, the amount of fish food added, and the number of fish and plants all factor into this. I have had planted tanks that received no nutrient supplements, even with my mineral-poor source water (GH is 7 ppm, or less than 1 dGH). But I also have a large tank where organics have been high (for mysterious reasons I have still not discovered) and the organic load has caused serious on-going problems. My point here is that increasing organics to this level that may indeed supply the plants' requirements (almost anyway), also brings on the problems for the fish and the biological system. Increased bacteria/diatoms (not the brown algae diatoms) causing hazy water permanently is only one manifestation.

Byron.

 

[NickAu]

First, nitrates. These are not as harmless as many seem to still believe. They are toxic, though less immediately so than ammonia or nitrite. They should be as low as possible, and reliable sources are now recommending 20 ppm as the maximum.

I agree, Just as an example Red Cherry shrimp can become sterile if kept in 20+ nitrates