Reading countless forum threads on low energy setups, water changes, fluctuating CO2 levels and algal blooms, I am amazed and somewhat despairing to discover that a direct and causal relationship between the above factors seems to have worked its way into aquarium folklore to the extent that it is now blindly accepted as actual scientific fact.
There is an underlying philosophy at work here one that pervades many pursuits that are thought to be underpinned by science, and not least is our great hobby (obsession) maintaining a healthy planted tank.
Unfortunately, it is more often than not, pseudoscience and not science that becomes conventional wisdom (accordingly conventional wisdom is often wrong) through nothing more than repeated use and familiarity, and then before too long we find ourselves preaching it as gospel no matter how scientifically implausible an idea it may be.
I think what is really going on is that we tend to associate truth with convenience and not necessarily scientific rigor. It is for example easy to blame the algae explosion in our lower energy tanks on the CO2 spikes supposedly associated with frequent and significant water changes than on poor husbandry.
So although the science behind this theory is convincing I think it is complete and utter nonsense, and for several very good reasons, not least those below.
1. Yes gasses do get compressed in a high pressure environment such as a potable water delivery system (pipes) but where does this supposedly significant increase in CO2 come from once the water exits the tap in our homes?
2. Surely the CO2 content of the water used to top up our tanks will be the same as it was at the beginning - in the reservoir - all that has happened is that the same amount of gas has re-equilibrated at atmospheric pressure?
This is why the “unscrewing the lid on the fizzy pop bottle” analogy is so inappropriate, the levels of CO2 involved are hugely different.
3. So where did all that extra CO2 come from – the extra CO2 that some pundits claim so upsets the balance of our tanks?
Bacteria in the pipes? I hardly think so.
4. For one thing if bacteria were so prevalent in our water supply system, as to make a significant contribution to its CO2 levels during transit, surely we’d all be dying of cholera and typhoid, or at the very least constantly mincing to the toilet with our butt cheeks firmly clenched...well surely we would...wouldn't we?
5. If the levels of CO2 were that high that they are capable of causing algal blooms and other mischief, wouldn’t our fish be gasping at the surface every time we did a water change?
6. Wouldn’t the daily fluctuations due to plant photosynthesis and respiration be of greater significance?
7. And do fluctuating levels of CO2 actually cause algal blooms anyway? Has it ever been proven beyond all reasonable doubt using scientifically rigorous and statistically significant research?
8. And as for all this leaving the water to degas overnight, and doing secret water changes when the algae aren't looking...please do me a favour.
Anyway, I could go on but won’t.
Regardless of the validity of the water change/CO2 theory I tend to think that if other parameters are well balanced a soil substrate/lower energy system should be robust enough to withstand the occasional temporary fluctuation without adverse effects.
Mine obviously is since despite changing 30% - 50% of the water twice a week I haven’t had any algal blooms and what is more I barely have to clean the glass. Check out the photos in the links below if you don’t believe me.
And just to finish, a cautionary note regarding causality, it’s very often not what you think. Take for example the butterfly effect:
Butterfly flaps wings and somewhere there’s a hurricane.
I prefer the alternative scenario:
Pseudoscientist flaps mouth and somewhere there’s a storm in a teacup.
There is an underlying philosophy at work here one that pervades many pursuits that are thought to be underpinned by science, and not least is our great hobby (obsession) maintaining a healthy planted tank.
Unfortunately, it is more often than not, pseudoscience and not science that becomes conventional wisdom (accordingly conventional wisdom is often wrong) through nothing more than repeated use and familiarity, and then before too long we find ourselves preaching it as gospel no matter how scientifically implausible an idea it may be.
I think what is really going on is that we tend to associate truth with convenience and not necessarily scientific rigor. It is for example easy to blame the algae explosion in our lower energy tanks on the CO2 spikes supposedly associated with frequent and significant water changes than on poor husbandry.
So although the science behind this theory is convincing I think it is complete and utter nonsense, and for several very good reasons, not least those below.
1. Yes gasses do get compressed in a high pressure environment such as a potable water delivery system (pipes) but where does this supposedly significant increase in CO2 come from once the water exits the tap in our homes?
2. Surely the CO2 content of the water used to top up our tanks will be the same as it was at the beginning - in the reservoir - all that has happened is that the same amount of gas has re-equilibrated at atmospheric pressure?
This is why the “unscrewing the lid on the fizzy pop bottle” analogy is so inappropriate, the levels of CO2 involved are hugely different.
3. So where did all that extra CO2 come from – the extra CO2 that some pundits claim so upsets the balance of our tanks?
Bacteria in the pipes? I hardly think so.
4. For one thing if bacteria were so prevalent in our water supply system, as to make a significant contribution to its CO2 levels during transit, surely we’d all be dying of cholera and typhoid, or at the very least constantly mincing to the toilet with our butt cheeks firmly clenched...well surely we would...wouldn't we?
5. If the levels of CO2 were that high that they are capable of causing algal blooms and other mischief, wouldn’t our fish be gasping at the surface every time we did a water change?
6. Wouldn’t the daily fluctuations due to plant photosynthesis and respiration be of greater significance?
7. And do fluctuating levels of CO2 actually cause algal blooms anyway? Has it ever been proven beyond all reasonable doubt using scientifically rigorous and statistically significant research?
8. And as for all this leaving the water to degas overnight, and doing secret water changes when the algae aren't looking...please do me a favour.
Anyway, I could go on but won’t.
Regardless of the validity of the water change/CO2 theory I tend to think that if other parameters are well balanced a soil substrate/lower energy system should be robust enough to withstand the occasional temporary fluctuation without adverse effects.
Mine obviously is since despite changing 30% - 50% of the water twice a week I haven’t had any algal blooms and what is more I barely have to clean the glass. Check out the photos in the links below if you don’t believe me.
And just to finish, a cautionary note regarding causality, it’s very often not what you think. Take for example the butterfly effect:
Butterfly flaps wings and somewhere there’s a hurricane.
I prefer the alternative scenario:
Pseudoscientist flaps mouth and somewhere there’s a storm in a teacup.