Based on ceg4048 statement: "If you add more CO2 then you need to add more nutrients." Does this means it not advisable to increase my co2 (without adjusting lights) to the limit of 30ppm so not to worry about it, without appropriately adjusting my nutrient dosing? or "If you add more nutrients then you need to add more CO2" does this also means that it is not advisable to dose EI based concentration (without adjusting lights) without appropriately adjusting my co2?
Hi,
As mentioned by the other posters, these are the general principles regarding the relationship between light/CO2/nutrients and they cover the range of combinations from low to high. So for example a low tech non-carbon enriched tank can get away with minute amounts of nutrient dosing because the CO2 level is low. If carbon was then added to the tank without adjusting the nutrient level upwards then nutrient defficiency would typically occur.
It has often occurred where the hobbyist uses a very low level of nutrients and CO2 where that particular combination results in the tank being CO2 limited. This may work fine until the CO2 is increased. The increased CO2 may then result in a higher demand for nutrition. If no more nutrition is added the tank may then become nutrient limited.
Whether we see problems in the tank as a result of changing one or more of these factors is a matter of severity of change. So for example, changing the injection rate from 1 bps to 2 bps may not make a difference, but changing from 1bps to 6bps may expose the new nutrient limitation.
Trying to determine quantitative values of change is difficult, so T.Barr decided it would be a better strategy to operate at the high end and simply remove the limits. So if CO2, nutrients were unlimited then the tank could withstand strong lighting. This is the basic principle of EI dosing which simplifies this aspect of the light/CO2/nutrient relationship.
In your chosen dosing scheme, Perpetual Preservation System, it is entirely possible that increasing the gas injection rate beyond the current limits may expose a nutrient limitation. Of course, we do not really know whether your tank is light limited, CO2 limited, or nutrient limited. This is the pitfall of applying general statements to a specific case. PPS is a very uncertain scheme because it depends a lot on measurement results of the nutrient levels, which is fundamentally uncertain. It could be, for example, that you water source is already high in nutrients so that even a large change in the gas injection rate does not cause any problems, or, the opposite might be true and a large injection change exposes nutrient related issues. I cannot predict, however, it's more important to be aware of the possibilities so that you understand what's going on and can take the proper corrective action if necessary.
To this end, it is also necessary to be able to determine what symptoms indicate a CO2 shortfall as opposed to symptoms that indicate a nutrient shortfall.
One thing for certain, as foxfish mentions, is that you never need to adjust the light intensity upwards. Excessive lighting causes more problems than it solves and reduces your margin of erorr , so if your lighting is low to moderate then you have much more room to make adjustments to either nutrients or to CO2 without incurring problems.
Cheers,