JMorgan
Member
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
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