Aluminum is used in many farms as screens, hatching trays and also as a construction material for some items of plant such as filters etc. The material is generally long lasting, but use in very acid waters should be avoided as this can lead to the build up of aluminum in the water, which is toxic to fish. It's use in seawater systems should also be avoided as the seawater oxidizes the aluminium. Where aluminium is not suitable, 304 or 316 stainless steel should be used. In some areas where there is an abundance of aluminium in the ground, and acidic waters prevail, dissolved aluminium can cause severe problems to fish. These problems most often occur where there is run-off from industry/mining activities