Article KH-PH and the chart to determine CO2

Is a higher range of co2 better/worse?
Meaning higher than the optium range?

Ex. My last test which was done some time back said my kH was 2.23 and my lighting is considered moderate-high (216w of t5 = 2.4wpg)...so according to this chart and matching it with my pH of 6.0 my co2 would be about 65 (HIGH)

 

Carbon dioxide
Carbon dioxide is dissolved in water in its molecular gaseous state; only 10 % is in the form of carbonic acid H2CO3. These two forms of carbon dioxide together constitute what is termed free CO2. The ionic forms, i.e. fixed carbon dioxide, are represented by the bicarbonate and carbonate ions (HCO3- and CO32- respectively). Their presence is important for the buffering capacity of the water. The amounts of CO2 present in flowing surface waters are typically in the order of a few mg per litre, and seldom rise above 20 to 30 mg per litre. In stagnant surface waters the CO2 levels are stratified because of photosynthetic assimilation by phytoplankton, the upper strata usually having less free CO2 than the lower strata. If all the free CO2 in the surface strata is used for photosynthesis, the pH of the water there may rise above 8.3, and in waters of moderate bicarbonate alkalinity to 10.0 and above during the daylight hours. Ground waters from limestone or chalk strata usually contain several tens of mg of free CO2 per litre, and this may be important where well water is used for fish culture.

The toxic action of carbon dioxide is either direct or indirect. The indirect action of both free and bound CO2 is exerted on fish through its influence on water pH, especially where, as described earlier, the values rise to toxic levels. Also, changes in pH affect the toxicity of those chemicals which exist in the dissociated and nondissociated forms of which only one is toxic, such as H2S and ammonia.

A direct adverse effect occurs when there is an excess or absence of free CO2. In waters of low oxygen content, such as where intensive biodegradation is taking place, or where fish are kept or transported in a high density, or when poorly aerated ground waters are used, free CO2 may reach harmful levels. In such cases the diffusion of CO2 from the fish blood into the respiratory water is reduced, the blood CO2 rises and acidosis develops. If the rise in CO2 concentration is relatively slow (e.g. over 1 day), fish can adapt to the acidosis by increasing the bicarbonate concentration of the blood. Adapted fish can then suffer from alkalinosis if returned to water of low CO2 content.

In water of low O2 and high CO2, where gaseous exchange at the respiratory surface is limited, the fish increase their ventilation rate, become restless, lose equilibrium, and may die. Twenty mg free CO2 per litre is considered the maximum permissible concentration for trout (higher concentrations can cause kidney problems) and 25 mg free CO2 per litre is the maximum for carp (if the acid capacity is 0.5 mmol per litre at a pH of up to 4.5). The sensitivity of fish to free carbon dioxide declines with increasing acid capacity of water.

However, the more frequent occurrence is a lack of free carbon dioxide in water. Carbon dioxide deficiency occurs when too much free CO2 is utilized for photosynthetic activity by the phytoplankton, or when the water used in thermal power plants is artificially softened or when water is aerated more vigorously than necessary with CO2 free air. Free carbon dioxide concentrations below 1 mg per litre affect the acid-base balance in the fish blood and tissues, and cause alkalosis. A lack of free carbon dioxide is particularly harmful to cyprinid fry when they pass from endogenous to exogenous nutrition. Cyprinid fry respire through their body surface and are unable to regulate their acid-base balance by gill respiration. A low partial pressure of free CO2 in water is conductive to a high CO2 diffusion rate from the body, leading to alkalosis and finally to death. If the fry of cyprinids suffer from free CO2 deficiency, they gather close to the water surface and show symptoms of suffocation even though the concentration of oxygen in the water is adequate (Taege, 1982).

Rick

 

okay, now I'm confused...I have excellent circulation and according to this chart HIGH co2...so should I be dosing with excel?
And what if anything can you do to lower your co2 and should I even bother? (everyone is doing fine...no one is favoring the surface like lack of oxygen).

 

I would be willing to bet you KH is low that you think therefore your CO2 is not as high as you think.

Rick

 

Tested with api liquid test kit?

 

When did you test last?

Rick

 

not quite 2 months ago

 

IMHO If it not broke don't fix it
Also keep in mind concentration of CO2 and O2 are independent of one another so high CO2 does not necessary translate to low O2 levels

Rick

 

I tend to agree when it comes to that (unless it's something such as ammonia ..or along those lines).