In many cases, the aquarium that gets dirty easily has a problem with water quality. For example, algae grows rapidly when nitrogen and phosphorus in the water increase while the problems of cloudy water and film on the water surface take place when more organic compounds are contained in the water. Besides, a rise in total water hardness leads to water stains due to calcium. As can be seen from these facts, the cause of contamination can be identified and appropriate actions can be taken by checking the quality of the aquarium water. This section introduces the check points of water quality relating to contaminated aquariums.
pH is a measurement of how acidic or alkaline the water is. A pH 7.0 is neutral and a pH lower than that is acidic while a pH greater than that is alkaline. The pH value of aquarium water varies depending on the substrate or layout materials, CO2 injection and photosynthesis of aquatic plants.
The point to be checked for pH is whether it indicates an alkaline condition while the lighting is ON during daytime. If the pH level is alkaline in such a circumstance, insufficient CO2 injection is suspected. This can be found out with Drop Checker. It is advisable to check TH (total water hardness) at the same time to see if the stones used as a layout material have an impact on the water quality
TH (total water hardness) is a sum of calcium and magnesium ions in the water. Basically, aquatic plants grow better in a lower TH environment while a TH level greater than 100mg/L tends to affect the growth of aquatic plants. In an aquarium environment, the TH level may rise from the effect of the substrate, sand and stones. In some cases, the tap water to be poured into the aquarium is high in TH. A high TH level tends to result in water stains between the water surface and the top end of the aquarium tank. In consideration of the impact on appearance of aquarium and growth of aquatic plants, it is recommended to lower the TH level by mixing Tap water with RO Water
COD (Chemical Oxygen Demand) test is mainly performed to measure the organic compounds in water and indicate the water contamination level. The COD level of aquarium water should ideally be as low as possible. The COD value rises with the increase in organic compounds in water due to fish or shrimp feces, leftover of fish feed and decayed aquatic plant leaves. Caution should be taken if the COD reading is 6 – 8 mg/L or greater.
COD can be lowered by way of water change, however it will go up soon under the conditions of excessive number of living organisms such as fishes in the aquarium, overfeeding the fishes or dirty substrate or filter media. In such event, appropriate actions should be taken such as keeping the living organisms in a separate aquarium and cleaning of substrate or filter media.
NO2 (nitric acid) is an important substance which is taken up by aquatic plants as nutrient. However, it can increase algae in aquarium if it is excessively accumulated. The organic matters contained in feces and leftover of feed are broken down into NH4(ammonium) which is harmful to living organisms.
NH4 will be converted into NO3 (nitrite) and finally into unharmful NO3 (nitrate) by nitrifying bacteria. NO3 is absorbed by aquatic plants as nutrient and therefore it usually is hardly detected in the water of aquarium with lush, healthy plants.
Detection of NO3, even at a low concentration, means that the supply rate of NO3 is higher than its absorption by aquatic plants. In this event, it is advised to get rid of NO3 by changing aquarium water. At the same time, the sludge buildup on the substrate and filter should also be removed.
PO4 (phosphate) leaches out of feces of living organisms or leftover of feed and will eventually be absorbed by aquatic plants as nutrient. Therefore, PO4 is also seldom detected in aquarium with lush plants just as the case of NO3. The aquarium in which even a trace amount of PO4 is detected may sometimes face a sudden increase in filamentous algae, blue green algae and other types of algae.
This algae problem is more prominent with PO4 compared to the case of rise in NO3. Getting rid of PO4 by way of water change is in fact an effective solution, but the problem will not be completely resolved unless the root cause, which is an excessive amount of living organ· isms or feed, is improved.
It is also important to remove the sludge buildup on the substrate and filter just as the case of NO3.