# Understanding adaptation to no Water Changes



## JMorgan (17 Apr 2016)

To recap what Ive gathered so far:

When plants have to deal with 4-8ppm CO2 typical of water without any CO2 injection, they produce more of an enzyme called rubisco (*Ribulose-1,5-bisphosphate carboxylase/oxygenase) *to help make more efficient use of the paucity of available carbon in the water. By contrast when there are either high or fluctuating levels of CO2 this enzyme based process becomes less efficient, because plants downsize their "rubisco factories". The plant gets "confused" as to how its going to obtain the CO2 it needs and, since it cannot react as quickly as simpler organisms, one result maybe more algae. Therefore the guidance is to avoid fluctuating levels of CO2 by just topping up evaporated water rather than doing water changes and/or to do infrequent minimal water changes if they must be done at all.

Doing this can result in some plants not normally associated with low-tech tanks being able to grow well if very very slowly.

While deliberately lacking in any technical depth, I hope the above is reasonably accurate?

Thanks to Darrel and other kind and helpful members here, I'm figuring out how I'm going to maintain several low-tech tanks using a 1/5 tap water 4/5 RO water mix to give me a TDS of between 80 and 100 ppm because the fish I have and intend to keep/breed in future are all soft-water species.

The issue or question(s) before me now are how to balance keeping a clean tank (which means some siphoning of the substrate) with minimising the fluctuations of CO2 when I replace the siphoned water. And how to provide the plants with what they need to grow (very slowly) while maintaining a lowish TDS.

Now I do appreciate that a kinda purist Walstad type tank just allows bacterial action to break down everything so it returns to the substrate/feeds the plants, but while I'm not super fussy I aesthetically like to get rid of the obvious excess crud via a quick siphon once in a while. Excess biomass is being removed by removing duckweed, trimming frogbit roots and replanting some stem plants when they hit the surface . . . So:

1) Currently I'm aerating the water in my RO barrel because I pre-heat it in the barrel to about 24˚C and aerating ensures an even temp. Am I thereby (unintentionally) adding CO2 through surface disruption - would I be better off not aerating it to minimise CO2 fluctuations? We're talking 10-20% water change every ten days to a fortnight - so maybe its too little to have much impact?
2) Given that the issue is fluctuation and not that more CO2 is bad, am I _better_ off aerating the RO water barrel, because it'll mean the CO2 ppm is much the same as the water in the tank going through two air driven filters?
3) In a nutshell how do I best minimise CO2 fluctuations ? I'm going to HAVE to do some water changes to gradually bring the TDS down anyway . . . even if I try not to clean the gravel too often . . .

Hope that makes sense


----------



## Tim Harrison (17 Apr 2016)

Wow...I think you maybe over thinking things a tad...http://www.ukaps.org/forum/threads/low-energy-water-changes-co2-algae-and-pseudoscience.21071/


----------



## JMorgan (17 Apr 2016)

Hey Troi - entirely possible! But that's the problem when Google searches are as likely to turn up dross and gems  Given that even a cursory glance at your thread promises to answer many of my questions and make my OP questions entirely redundant (for which I am extremely grateful!) please feel free to use your god-like moderator powers and delete the whole thread 

In my defence I'm sure that this whole CO2 fluctuations with water changes advice/issue/problem was something Tom Barr had given his seal of approval too in recommending the following thread: http://www.sudeepmandal.com/hobbies/planted-aquarium/low-tech-planted-tank-guide/ 

Which is why I gave it credence . . . and since I was possibly expending energy in making things more difficult for myself I wanted to address it.


----------



## Tim Harrison (17 Apr 2016)

Haha...it makes a refreshing change to read a post that is obviously researched. I just have a different point of view
And Tom Barr (plantbrain) is also a contributor to the thread I linked...he goes in to some detail.


----------



## Mortis (25 Apr 2016)

Hey you should get a cleaner crew of a few RCS and maybe some nerite snails to help break down the larger waste into smaller bits that can be more easily broken down further by bacteria.
While I generally dont prefer to use them, try a bacteria product like Seachems Pristine or Microbe lift that claim to break down detritus and sludge faster.
If you do want to do a bit of siphoning without water changes or top offs then your only option is to use a battery powered gravel vac like the one from Eheim or you can run your siphon tube through some strainer into a bucket and add it back to the tank. 

I think another option for you to keep CO2 stable would be to run it at low bps 24/7


----------



## dw1305 (26 Apr 2016)

Hi all, 
I'm with "Troi" on this, I change the water regularly in all my tanks. 





JMorgan said:


> Given that the issue is fluctuation and not that more CO2 is bad, am I _better_ off aerating the RO water barrel, because it'll mean the CO2 ppm is much the same as the water in the tank going through two air driven filters?


 Any RO water that has stood for a while (or been aerated) will have CO2 levels in equilibrium with atmospheric levels. 

When you have a planted tank CO2 levels will always fluctuate through a diurnal cycle, as photosynthesis depletes CO2 during the light period and respiration replenishes it at night. 

Have a look at <"Fish health in relation to no water changes in low tech tanks">.

cheers Darrel


----------



## rebel (26 Apr 2016)

dw1305 said:


> Any RO water that has stood for a while (or been aerated) will have CO2 levels in equilibrium with atmospheric levels.
> l


Would this equilibriate to about 4ppm or so?


----------



## alto (26 Apr 2016)

dw1305 said:


> Hi all,
> I'm with "Troi" on this, I change the water regularly in all my tanks.


Me three ... if you don't want to change water please don't keep any livestock, just stick with plants & whatever microflora develops


----------



## sciencefiction (26 Apr 2016)

Me four....
When you stop doing water changes, if the tank has any sort of evaporation that requires top ups weekly or bi-weekly, your TDS and GH will go through the roof, your Kh will keep dropping. One day the tank will just crash. One will notice when majority of the fish start gasping and dropping like flies from various issues.
If you keep a really tight lid that prevents any sort of evaporation, the TDS, Gh and KH all will be dropping. If your initial water is very soft, it will become extremely acidic and prone to wild fluctuations.
The only solution is regular water changes to keep it stable. Plants won't prevent that.  In a moderately stocked tank that has shredders such as shrimp and snails you should never see "crud" to siphon. I almost never siphon my low techs. I just do large weekly water changes and clean the filters. The bottom has never been dirty in the slightest.

As for fluctuating co2 levels...I don't know where Tom Barr came up with that idea. In years of practicing what he preaches against,  it turns out there are no issues whatsoever in doing large water changes on a low tech tank. It doesn't cause algae and the variety of plant species you can grow is not dependent on that  at all.
But wouldn't want to influence you in any way. Test your own theory to see if it works for you. That's how we learn what to trust.


----------



## dw1305 (27 Apr 2016)

Hi all,





rebel said:


> Would this equilibriate to about 4ppm or so?


The equilibrium value <"would theoretically>" be ~0.5ppm, but I think it will be a bit higher in practice.

cheers Darrel


----------



## BigTom (27 Apr 2016)

To echo what the others have said... I ran the old Bucket without water changes initially and had no algae. I then switched to regular water changes and still had no algae. No reason not to do them. 

Sent from my HUAWEI GRA-L09 using Tapatalk


----------



## JMorgan (28 Apr 2016)

Many thanks for all the interesting and informative replies and links to previous discussions/threads. 

I'm all for low maintenance, but having planned on doing regular water changes I was more than a bit dismayed to read that I should be minimising fluctuations of CO2 by avoiding water changes with low tech set ups. Since this chimes with Diana W's views (though with a different rationale) I assumed it must be True with a capital "T" . . .  from then on I was concerned with damage limitation and hence this thread. 

It didn't occur to me - as it certainly will in future - that other's experience would show the advice from Tom Barr to be at best not universally true and at worse simply wrong.  I accept that folks have probably learned a thing or three since Diana wrote her book, but expected Tom's views to be more current and didn't expect him to state ideas as facts that would be flat-out contradicted in other folk's experience.
cheers all


----------

