# water changes in a low tech tank



## a1Matt (3 Mar 2009)

I understand that it can be better in a tank with no added CO2 to NOT carry out regular water changes.

I think this is because 1/tap water can contain high CO2 and the fluctuating levels can contribute to an algae outbreak. 2/ growth rates are much slower so the filter and plants 'break down all nasties' to the point that water changes are not needed.  For simplicity lets assume there is no nitrate,phosphate, potassium, etc buildup from dry ferts or the like. 

So up for discussion is... 

Is my understanding correct? Are WC's really not needed, or just not needed as frequently. 

and...

Has the idea of letting tap water sit for some time (how long 2hours, 2 days?) so that the CO2 dissipates, then adding it to the tank been considered.  That way fluctuating CO2 levels ceases to become an issue  :!: 

I have been going without water changes for a couple of months and all is going great (still dosing dry ferts albeit 5x less, growth has slowed right down but plants are doing well - some better, some worse! Most interestingly fish and shrimp are a LOT healthier looking).  I just have a niggling feeling that on along term basis no (or say only 6 monthly) water changes is not ideal.


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## ceg4048 (5 Mar 2009)

Hi,
   You could set the water out and de-gas the CO2 but why bother? It's supposed to be a low maintenance tank right? The water is being recycled in the same way that the Russian cosmonauts recycled their urine to perfectly drinkable water for months in their spaceship. Toxic buildup is absorbed by the plants so this scenario the perfect example of sustainability. I'd believe your fish and shrimp. If they say things are OK then things are probably OK. A twice yearly change will normally suffice, so every 6 months would be fine if it gives you peace of mind. 

The niggling feeling is likely the residual toxic effects of having spent so much time hard wired to The Matrix.  8) 

Cheers,


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## a1Matt (6 Mar 2009)

That is good to hear, if it is good for the cosmonauts then it is good for me.  Thankyou Morpheus for showing me the door again


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## hellohefalump (14 May 2009)

What about nitrate build up?

I'm thinking of starting up a low tech chocolate gourami tank, so the fish will be sensitive, and eat messy food.


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## JamesM (14 May 2009)

a1Matt said:
			
		

> ... Most interestingly fish and shrimp are a LOT healthier looking...


Yup, I'm still amazed at the health of my fish, and I'm just over 12 months without a single water change. In this time I've lost one fish, and that was due to him being stuck between some hardscape (which has now been moved slightly to avoid it happening again).

Thing is though, I'm getting a lot of plants starting to break down all of a sudden this last month.. I'm not sure what the problem is as nothing has changed, but I'm hoping to break it down soon anyway.


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## strolgen (14 May 2009)

JamesM said:
			
		

> a1Matt said:
> 
> 
> 
> ...



I have one species of cryptocoryne ( brown leaves ) which melted away last week even though nothing change in the tank. Another cryp species ( green leave ; sorry for the poor name description ) is doing fine though. 
Other plants are doing fine: varieties of fern and ... Eleocharis acicularis! ( not a thick carpet but good enough for me !)

Tank is being run for 3 months without water change so far.


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## ceg4048 (14 May 2009)

hellohefalump said:
			
		

> What about nitrate build up?


Well, if my name were Cryptocoryne and if I heard about nitrate buildup, I'd say; mmm..yummy! Can we have some phosphate buildup as well Mummy?  



			
				hellohefalump said:
			
		

> I'm thinking of starting up a low tech chocolate gourami tank, so the fish will be sensitive, and eat messy food.


This is easy to fix. Avoid overfeeding. The fish will be more sensitive to the ammonia caused by overfeeding than they will be to nitrate.

As long as you have sufficient plant mass they will clean the tank and will control buildup of toxic, semi-toxic and non-toxic components in the tank. This is the whole agenda of plants in the first place. As long as you don't illuminate the tank with too much light, the plants will not be driven to uptake mass quantities of nutrients and CO2.

With good plant mass, and depending on stocking levels and feeding regimen, you may actually need to supplement NPK and traces a few times per month.

Cheers,


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## JamesM (14 May 2009)

ceg4048 said:
			
		

> Well, if my name were Cryptocoryne and if I heard about nitrate buildup, I'd say; mmm..yummy! Can we have some phosphate buildup as well Mummy?


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## aaronnorth (15 May 2009)

lol Clive,

with some exceptions most fish can survive Nitrate levels into the hundred's, and Tom has tested 140ppm with Shrimp. I can find some papers if you want?


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## a1Matt (15 May 2009)

I am 5 months (or thereabouts) into no water changes now, so thought I would chip in  

@strolgen, my crypts also starting melting abut 3 months into no water changes.  I started adding calcium and they came back to life quite quickly.  If you buy 'gypsum' from an ebay brew shop it is a very cheap source of calcium. Am currently dosing it at 1/8th teaspoon weekly into 160litres. I added 1tsp a week for the first two weeks to allow for any surge uptake.  (It does raise GH which was an added bonus for me as my green shrimp need a highish GH to breed.)

@Aaron, I inadvertently (but consistently!) overdosed all my dry ferts for the first couple of months of going low tech. I would guess that I easily hit at least 100ppm of nitrates before I realised   No harm was done to any flora or fauna  8) This was a very comforting accident! For instance... say I know I am going to be going away for, lets say, 3 weeks - I can then just double my weekly dosing in the 3 weeks leading up to my break. 

@Clive - yummy yummy indeed


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## neelhound (26 Jun 2009)

i would reccommend if there are fish in there to do at least one at the 6 month mark, im no plant expert but for the fish its better safe then sorry,if lets say after 2 years you hit toxic levels for fish because the plants arent taking in enough, its really hard to get rid  of even with w/cs and it goes down better with more frequent w/cs.But this is just in terms of the fish


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