can you have too many plants in a low tech tank

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hey.
I've been wandering about whether a low tech tank could be too heavily planted for its own good?
Obviously the most limiting factor in low tech is co2. I know ppl have a light break to allow levels to replenish again but surely at some point plant mass could be too great for even this to help?
 

aaronnorth

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plants create more of the enzyme rubisco to compensate,
the only advantage i know of for having a siesta period is to allow CO2 levels to replenish (ie, when using a fermetnation kit).
 
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hi arron.

I'm aware of the plants compensating for low co2 with the production of rubusco.
But what happens when co2 is completely depleted?
the lighting break obviously would work in a tank with no co2 added for the same reasons as a tank with diy co2 would it not?
surely the larger the plant mass the quicker the available co2 will be used?
Hence the original question!

Or are the above moot points and the water takes in the "ambient" (cant think of a better word for it!) co2 faster than even a tank with massive plant mass could use?
 

aaronnorth

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But what happens when co2 is completely depleted?
the average CO2 levels is approx 4-8ppm (without CO2 injection). Plants will be growing very slowly that they will need hardly any CO2 at all, if that does drop to 0ppm which isnt likley because surface agitation will be keeping the air/ water equilbrium at 4-8ppm.

Unless you have no surface agitation at all then CO2 levels i doubt will ever be 0ppm. there is also respiration taking place bewtween bacteria and not forgetting plants, which will be adding more CO2 to the water.

the lighting break obviously would work in a tank with no co2 added for the same reasons as a tank with diy co2 would it not?
equilibrium would prevent this, so it will be around 4-8ppm constantly. This is why you shouldnt do water changes, as it will fluctuate the levels.
so there is no need to allow CO2 levels to replenish.

surely the larger the plant mass the quicker the available co2 will be used?
true, but as above growth is very slow, so little carbon needed, rubisco, and respiration all help towards CO2/ carbon be non-limiting.

I am sure someone will correct me if i'm wrong ;)

Thanks, Aaron
 
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ok,
so when the lighting is increased to the point of "needing" extra co2, its not at all because the co2 is getting depleted but purely that the concentration isn't enough?
 
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