# Interesting fact about natural CO2 in Lowtech/Walstad



## Dusko (15 Jan 2009)

Hi all,
long time no see    howyalldoin' ?!

Thanks to some very stressful time in my professional life (which also effected my private life) I neglected all my planted aquariums for a long time now (approx 8 month). Beside feeding the fish and occasionally removing some overgrown plants (especially the floating ones) and dumping in every now and then a bit of NPK+traces (every 2 month) I didn't pay much attention to my planted aquariums. 

Knowing that I will neglect them made me introduce floating plants (for NH4 removal) to 3 of them but one. 
NOTE; No water change, No filter cleaning, Only water top-up! *Filters were so dirty which reduced the pump's circulation!*

3 tanks (2 low light and 1 Hi-light) with floating plants didn't get any algae at all, slow submersed plant growth but healthy leaves.
The 4th tank (medium light) without any floating plants did have algae on the glass and some BBA (but not much) on the Hygro leaves.

I would like to discuss the 54 litres High-light Low Tech/Walstad tank  8) 
This aquarium was set-up as a Hi-Tech at first but after the CO2 malfunctioning creating huge Green Water (Algae Bloom) problem I disconnected it and introduced lots of floating plants like Salvinia natans, Azola caroliniana and some Duck weed which in fact did help very fast in removing all the green water (I think I have a thread about it somewhere on this forum).
I never connected the pressurized CO2 again and kept the floating plants creating a Walstad Low Tech.
I used potting soil for this tank.

I left the CO2 Drop Checker in out of pure laziness.

Yesterday I FINALY decided to FIX my tanks a bit and was shocked to see my drop checker showing high CO2 levels in that Hi-Light Low-Tech aquarium... light green color !!!   




Tank photo made after the tank maintenance (plant pieces floating all over sorry);




Getting such levels of CO2 in a low tech is amazing! What are your thoughts on this?

Kind regards, Dusko


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## GreenNeedle (15 Jan 2009)

My thoughts are that either something is creating CO2 within the aquarium, which I doubt.  The DC hasn't been changed for while and is showing other acids changing the Ph reading or that the initial 4dKH solution is wrong!!!

The natural level in your aquarium would be about 3ppm before plants consume some and this is nowhere enough CO2 to even change from blue.  It will however try to maintain equilibrium and gaseous exchange will keep 'topping' it up to the 3ppm.

Was this after a water change?
How long has the solution been in the DC?
What source is the 4sKH from and how old is it?

AC


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## Dusko (15 Jan 2009)

> My thoughts are that either something is creating CO2 within the aquarium,



I have 2cm deep potting soil layer which according to Diana will give lots of CO2 in such set-ups (less light because of the floating plants)



> The DC hasn't been changed for while and is showing other acids changing the Ph reading



Yes, this could be it since I have never changed it since started. I didn't even remove the 2 HOB filters nor the ceramic disc CO2 diffuser, as stated before I totally neglected my tanks.



> Was this after a water change?
> How long has the solution been in the DC?
> What source is the 4sKH from and how old is it?



1.No it was before the water change.
2. mmm...4 month approx
3. Tap water 5KH not 4KH

I have changed the DC solution today so will wait and see will it change from blue to green.




Thanks


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## JamesM (15 Jan 2009)

When I changed my 4ft tank from high tech to low tech I left my DC in too, and it stayed green for months. As soon as I changed the liquid it refused to go green at all, so I'm going to agree with Andy on this.

This low tech tank gets no water changes either, and I have no algae whatsoever. No floating plants either.


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## aaronnorth (15 Jan 2009)

JAmesM said:
			
		

> When I changed my 4ft tank from high tech to low tech I left my DC in too, and it stayed green for months. As soon as I changed the liquid it refused to go green at all, so I'm going to agree with Andy on this.
> 
> This low tech tank gets no water changes either, and I have no algae whatsoever. No floating plants either.



When my CO2 stopped working the DC stayed green, and when i changed the solution stayed blue :!: 

Although wheni got it working again and the CO2 is switched off at night via a solenoid, it has always returned blue in the morning   Strange...


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## Dusko (15 Jan 2009)

> When my CO2 stopped working the DC stayed green, and when i changed the solution stayed blue :!:
> 
> Although when i got it working again and the CO2 is switched off at night via a solenoid, it has always returned blue in the morning  Strange..



You see when I switched off my CO2 the DC turned back to blue!
That is why I reacted with surprise when DC turned green after so many month


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