Construction managers, also called general contractors or project managers, typically do the following: 1  Prepare and negotiate cost estimates, budgets, and work timetables. 2  Select appropriate construction methods and strategies. 3  Interpret and explain contracts and technical information to workers and other professionals.
Denitrification is the process that converts nitrate to nitrogen gas, thus removing bioavailable nitrogen and returning it to the atmosphere. Dinitrogen gas (N2) is the ultimate end product of denitrification, but other intermediate gaseous forms of nitrogen exist (Figure 7).
The third major cause of unexpected ammonia and nitrite spikes is old tank syndrome. This arises when tanks are not given regular partial water changes and are simply topped up instead when water evaporates. Over time nitrates build up, carbonates deplete and the water acidifies.