A: Iron bacteria changes the form of mineral iron from soluble (not usually visible) to insoluble (visible). When water is pumped from a bore hole that contains Iron bacteria the iron becomes visible in the water. The visible iron accumulates as red/brown slime in the pipes and fittings.

Use this simple method to check for visible (insoluble) iron:

1. After a period of idleness (>12 hours) start the bore hole pump and gather from a suitable point at the bore head a water sample. The water sample should be representative of that which has been in the bore hole for the full 12 hours. This means the sample should be collected within a few seconds of the pump start. In badly contaminated bores a slug of brown material is usually observed in the water column within the first few seconds. Ideally this material is collected for analysis and is particularly good for bacterial detection by microscope. Send this sample to the lab for testing. If no slug was observed miss (ii.) and go to (iii.)
2. Allow the pump to run for a further >10 minutes and collect another sample at the same point. The new sample will be water that is new into the bore hole and can only have had contact with any microbes for the time it passed though the equipment etc. This sample is representative of the normal water flow/quality.
3. To allow us to see the insoluble (visible) iron as it would pass into the irrigation or storage system a very fine micron filter (0.45 Um) is used to filter the insoluble iron from the water. It is useful to do this at the time of collection so that when the sample goes to the lab iron can be measured in both samples. The subtraction of the soluble from the insoluble (which ever is greater) Will give a good indication of the severity or type of problem that may exist. It may be necessary filter up to a litre or a least until the filter will not allow anymore water through.
4. A filter membrane that is coated in brown material after a small amount of water has passed through is suggests a high level of insoluble iron and conversely a large flow indicates a lesser problem. However it is important to note that under normal circumstances there should be none or a very small amount detectable iron by this method. Calculate the amount iron deposited in the irrigation system by the difference in the types of iron.
5. Should the water sample contain mostly insoluble iron then further oxidation would only have superficial benefits in expelling the remaining soluble iron. While high levels of soluble iron would benefit from additional aeration to assist with oxidation and precipitation. Iron bacteria cause the water chemistry to change and it is questionable whether air will be and advantage to enhance the quality of the water further. In fact further oxidation may add to the slime that simply floats atop the water storage.

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