water-saving water-change idea?

**juggler** · 8th Jan 2003, 12:10

I have this idea. Say you have two similar sized planted tanks:

Tank A: Planted tank with high bioload or bare tank with LH or Discus. ==> high NO3, PO4
Tank B: Planted tank with very low bioload. ==> very low NO3, PO4.

So weekly or fortnightly, the partial water change done from tank A is poured into tank B and vice versa.

So excess nutrients in tank A is reduced and the low nutrient for tank B is increased. You only need to dose the extra K, Mg and trace elements for both tanks.

And you save on water.

Workable?

**Allen_1971** · 8th Jan 2003, 12:18

I don't think so KF... off hand I can think of 2 things

1. there will be a one time exchange of disease between your 2 tanks causing them to be exposed to each others problems

2. More importantly, water changes are essential for removing other nutients which are piling up in our tank... not just NO3 and PO4. Case in point would be SO4... I assume that you dose K2SO4 in both tanks... as such, if you dose k2SO4 to achieve K of 20ppm, you can roughly 24ppm of SO4... If you do water changes each week you will keep this level in check with it finally maxing out at a fixed level. If you just keep switching water, your SO4 levels will just start to pile up with virtually no limit.

Perhaps it would be possible to do what you suggest on alternate weeks and do water changes fortnitely. However, I still think it would compromise water quality somewhat... Perhaps even more so for Dissolve Organic Compounds which tend to feature at very high levels in planted tanks.

**TTL** · 8th Jan 2003, 19:45

Well, I got 2 x 2ft tank and I change 20% of both and I been thinking of,

1) draw out 20% frm planted tank &amp; pour to my family plants along the corridor
2) draw out 20% frm my discus tank (usually full of discus ****) and tansfer to my planted tank.
3) pour matured clean water to discus tank.

I will bring the nutrient frm discus tank to planted while maintaining a clean water for my discus. Dunno this will work.

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**Allen_1971** · 8th Jan 2003, 19:48

I think it depends on your tank conditions...

I assume you discus tank has High N. If your planted tank is a low N tank, then it might be a possibility... but if your planted tank has high N as well, then its probably a bad idea... Water changes are needed to get rid of waste... i.e. anything in excess... is what you propose doesn't do that, then forget it.

**geoffrey** · 9th Jan 2003, 17:22

I would think doing water change between longer interval a better option. Say like once a month or once every 2 months.

**Allen_1971** · 9th Jan 2003, 17:42

Geoffrey,

I actually think the greater the frequency of your water change the better... i.e. I would rather change 10L/day than 70L/week.

Still without spouting out my reasons for thinking this way, I would be keen to hear why you think less regular changes are preferred?

**geoffrey** · 9th Jan 2003, 18:14

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On 1/9/2003 5:42:08 PM

Geoffrey,

I actually think the greater the frequency of your water change the better... i.e. I would rather change 10L/day than 70L/week.

Still without spouting out my reasons for thinking this way, I would be keen to hear why you think less regular changes are preferred?
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Mine is plainly an economic reason. How I wish dad is like Donald Trump!

And because of that, I have the tendency to find excuses or reasons to rationalise the action I want to take, until hopefully someone corrects me. Kind of like a case of cognitive dissonance.

Alright, here is how I figure it. Our fear is a tank's nutrients might build up to an undesireable point over a long course of dosing right? Now major ones like N and P can be measured thru PO4 and NO3, and as for micros thru Fe. I am with the presumption that Seachem's liquid fert or Dr M's Aqua (no PMDDs) are formulated with all the essential elements balanced for most plants (I stress, most plants but not all). So plants will uptake them quite proportionally. I assume then if N or P is low, most macros would also be low and if Fe is lowered, most micros will also be lowered. Hence if we measure these parameters and if they are within the specification we want them to be, I assume nothing is building up. Choon Bo?

How's that for an excuse?

**DEA** · 10th Jan 2003, 08:56

idea is idea
but we're assuming that only NPK etc is in the water
what allen said about disease is very pertinent
ALSO, like i said, we're ASSUMING only NPK etc is the water
there're plenty of things that fish excrete that bacteria in our tanks may or may not be able to metabolise into harmless forms
which is why i always advocate changing water

so...
once that builds up
hohoho
get me?

**geoffrey** · 23rd Jan 2003, 11:04

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On 1/10/2003 8:56:28 AM

idea is idea
but we're assuming that only NPK etc is in the water
what allen said about disease is very pertinent
ALSO, like i said, we're ASSUMING only NPK etc is the water
there're plenty of things that fish excrete that bacteria in our tanks may or may not be able to metabolise into harmless forms
which is why i always advocate changing water

so...
once that builds up
hohoho
get me?
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Sorry it not me so long to decide to speak against this.

Personally I feel no amount of water change is going to help reduce bacteria buildup. Water change is only going to dilute excess inorganic materials such as our excess K2SO4, KNO3, Fe etc. It is not going to dilute bacteria (they are alive). You may think you can remove alot of them with a 50% or a 100% water change but bacteria clinched on surface near the substrate, wall and water surface. They multiply immediately after a water change. Ever notice how fast the biofilm appears the next day after a water change? Why quarantine diseased fish instead of continuous water change?

My argument for a water change is only to dilute organic chemical buildup as a result of the metabolic cycle in the removal of dead organic particles and organisms in the tank rendering it more acidic from the organic acids /compounds they produce in the process.

Lake Tanganyika and Malawi haven't had their water change for eons except for the occasion top up from the rain for evaporation and that resulted in their exceptionally hard water characteristic (inorganic - lime) but bacteria and protozoa etc abound but their flora/fauna still flourish.

Please challenge my view. Want to learn more.

Disclaimer : I have not succeeded in a plant tank yet.

**Allen_1971** · 23rd Jan 2003, 11:46

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From an Earlier post:

Alright, here is how I figure it. Our fear is a tank's nutrients might build up to an undesireable point over a long course of dosing right? Now major ones like N and P can be measured thru PO4 and NO3, and as for micros thru Fe. I am with the presumption that Seachem's liquid fert or Dr M's Aqua (no PMDDs) are formulated with all the essential elements balanced for most plants (I stress, most plants but not all). So plants will uptake them quite proportionally. I assume then if N or P is low, most macros would also be low and if Fe is lowered, most micros will also be lowered. Hence if we measure these parameters and if they are within the specification we want them to be, I assume nothing is building up. Choon Bo?
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I don't agree with this geoffrey... each macro element has its own level of uptake depending on your tank conditions. Relying on N, P to guage macros and Fe to guage Micros is not sensible. Consider this...

Case1 :
My tank for some reason has a magnesium deficiency. Now a magnesium blocks uptake of iron. So I measure Fe and its fine... not cuz my plants have enough iron, just that it isn't consumed due to the Mg Deficiency. In this case, a Macro nutrient affects the level of a micro nutrient.

Case2 :
Similarly, consider using a heavy bioload tank where N is out of control. N and P will probably be high, but heck I could suffer a calcium deficiency... why? because the water is soft. and Calcium is a Macro nutrient.

Case 3:
My bioload is high, but my tank is heavily planted. Also the fert I use has insufficient K. So N is low and P is high and but K is low. Moreover, due to K deficiency, all plants photosythetic activity is slowed... i.e. lots of other nutrients not used...

So what I'm saying is this... you can't use just 1 or 2 nutrients to judge the whole range. The best and clearest indicators are your plants.

Coming back to the original topic of swopping water... just because one tank has no N and the other tank has too much doesn't mean that swopping water between the two tanks will balance off all the macro nutrients... it just mean you balance of the N.

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Personally I feel no amount of water change is going to help reduce bacteria buildup. Water change is only going to dilute excess inorganic materials such as our excess K2SO4, KNO3, Fe etc. It is not going to dilute bacteria (they are alive). You may think you can remove alot of them with a 50% or a 100% water change but bacteria clinched on surface near the substrate, wall and water surface. They multiply immediately after a water change. Ever notice how fast the biofilm appears the next day after a water change? Why quarantine diseased fish instead of continuous water change?
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I think when DEA mentioned disease he wasn't talking about bacteria buildup. If tank A has suffered a particularly bad bout of disease which killed lots of fish, its likely the surviving fishes have developed some immunity to the disease. Now do a water swop with Tank B, and you introduce that pathogen to tank B and go through the whole issue again.

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My argument for a water change is only to dilute organic chemical buildup as a result of the metabolic cycle in the removal of dead organic particles and organisms in the tank rendering it more acidic from the organic acids /compounds they produce in the process.
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If you consider the amount of stuff in our water that we put in... and consider the relatively small volume of our tank. Then consider the decay of organic material in our tank... you realize that theres lots of stuff that really isn't great for healthy fish/plants. Most fishes live in an environment where there are constant flows of water in and out... this automatically serves to &quot;dilute&quot; and remove unwanted substances from the water. Water changes serve a similar purpose. A single large water change would serve as a good diluting/remova

**geoffrey** · 23rd Jan 2003, 12:09

Glad I disputed this now. Better late than never. Looks like water change this Friday is on. Thanks Allen.

**Fei Miao** · 23rd Jan 2003, 12:18

just my 2 cents worth, i used my tank water for my potted plants[

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**juggler** · 23rd Jan 2003, 12:32

I am sure there are harmful bacteria in Lake Tanganyika. But the place is so big that fish are able to swim away from infected areas. Just like if we keep away from crowded areas, we have lesser chances of cathing flu etc. Most important is that fish are healthy so they are more resistent to disease.

For this discussion, can I add one more point. The minute amount of chlorine present in tap water can help to kill off some bacteria when you do partial water change.

**geoffrey** · 23rd Jan 2003, 12:40

Talking about chlorine, does plants uptake them in its element state, if not, what is the source of Cl in our tank? Substrate? Noticed Dr M's Aqua and Micro don't have any chloride/chlorine in them. Is Cl macro or micro?

**Allen_1971** · 23rd Jan 2003, 13:43

hmmm... good question. I'm not 100% sure, but any source of sodium would provide Cl. Perhaps our fish food has some sodium? Just guessing

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**vinz** · 23rd Jan 2003, 13:48

Don't forget evaporation does not remove anything except liquid water. Any impurities are left behind.

**Allen_1971** · 23rd Jan 2003, 13:55

Agreed, but with an ecosystem like lake tangayika, its probably in a state of equilibrium... i.e. the biological processes present are more than able to meet the demands of the fishes present... hehehe and they don't have a great big aquarist in the sky arbitrarily dosing 20ppm of K every week... i.e. whats in the ecosystem today is present through natural processes/events which in turn are taken care of by other natural processes thus maintaining a livable environment for the inhabitants of the lake.

**juggler** · 23rd Jan 2003, 14:37

Cl (chloride) is a micro. In Diana's book, the serves the plant function in &quot;Osmosis, charge balance, photolysis of water&quot; -- whatever that means. [

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**geoffrey** · 23rd Jan 2003, 14:47

Wonders why Dr M did not put them in his concoctions. Maybe he knows our water already have them. Or maybe he knows that people like us and Allen would use salt from our kitchen....hehe.