Well, poor CO2 is manifest in various forms. It's entirely possible that your injection rate is OK, but that your flow rate and method of distribution is poor.It can easily be that certain locations in the tank have adequate CO2 and that other locations are virtually starved of CO2. This happens all the time, so having a green dropchecker is not the ultimate indicator.
Distribution techniques also affect the "When" of CO2 concentration level, so that the CO2 concentration at a particular location is poor at lights on but OK at lights off. Since CO2 at lights on is much more important than it is near lights off, it's very easy to be deluded into thinking that your overall CO2 is OK, when in fact it might be highly problematic.
Getting good growth performance therefore means that you need to solve the "How", "Where" and "When" riddles of your tank. So although inline devices are generally better than in-tank diffusers, if your flow rate and distribution methods are sloppy you can still have lots of problems.
easerthegeezer said:
i often wonder if i get enough co2 into the water as i had a bad experience when i started and lost some bamboo shrimp and a gourami, i had plenty of co2 but no surface movement so no o2
This is another misconception regarding planted tanks. Plants, when healthy oxygenate the water much more than can ever be achieved by surface movement or aeration, therefore it is impossible that the shrimp died due to poor surface movement. The shrimp died of CO2 toxicity which affect their ability
to use the Oxygen that is present.
There are a couple of possible reasons shrimp are more sensitive to CO2 than fish. The first possible reason is that shrimp have an "Open Circulatory System", whereas fish have a "Closed Circulatory System". A closed system means that blood is contained within tubing and it is always kept separated from the tissues. Tissues are bathed in their own fluid produced by the Lymph system. That means blood never actually touches the tissue. Oxygen is delivered to the tissue by small capillaries in a "drive-by" fashion, wherein the Oxygen diffuses through the thin walls of the capillary, and CO2 diffused from the tissues into the capillary. This closed system ensures positive gas and nutrient delivery and positive waste collection. It's very efficient. On the other hand, in an Open System such as inverts typically have, there are no blood vessels, no tubes. The tissues are bathed in a combination of blood and lymph fluids. The heart is in a fluid filled cavity and the liquid squirts out into other cavities surrounding the tissue. In some cases the animal has to move it's limbs in order to help squeeze the cavities and to get the fluid back to the heart. Oxygen has to work it's way through the cavities and CO2 has to work it's way out DIY fashion. This renders the shrimp less able to positively rid itself of CO2.
A second possibility is that fishes blood uses a specific Oxygen transport protein called Hemoglobin, which is constructed of an Iron base and is a very efficient Oxygen carrier. Shrimp blood uses a much less efficient protein called Hemocyanin and this protein is copper based. It's very efficient at cold temperatures but much less so at tropical temperatures. As the fluid in the shrimp becomes more acid due to CO2 the Hemocyanin, which is already not very efficient, becomes even less capable of attracting and carrying Oxygen to the tissues. So gas exchange would become more difficult for inverts than it is for fish.
As a result of their greater susceptibility to hypoxia and hypercapnia therefore, shrimp are best kept in a Non-CO2 environment, but if you are injecting CO2 you need to be much more attentive to maximizing the efficiency of CO2 delivery to the plants by having high flow, excellent and even distribution which will generate more Oxygen from a lower gas concentration level.
Cheers,
