Odyssey
®
Xtreem
Capacitance Water Level Logger
User Manual
Reading Higher Than Actual on Falling Water Level
Sediments or suspended solids are forming a coating on the Teflon sensor. This deposit will hold a
film of water and cause a slight elevation of the reading. This type of error will only be a problem
when the rate of movement of the water is high. For slow movement in the water level the sediment
will dry before it can cause a significant error in the reading.
Frequent sensor cleaning is the best method to reduce this type of error. It will only be a problem in
water that is very heavily laden with silt and has a fast rate of decline.
Pressure differentials can be created in a stilling well by incorrect positioning of the stilling well in
flowing water. This may cause elevation or depression of the reading depending on the positioning of
the water inlet holes in the stilling well. Try to position the water inlet holes so that the stream flow
has minimal effect on the water level inside the stilling well. A bottom vented stilling well will generally
overcome this problem. A copper water inlet tube will help to lessen the problems of algae deposits in
the stilling well (Copper is algaecidal).
Reading Lower Than Actual on Rising Water Level
This type of error may be caused by deposits on the Teflon that are non-wetting. The result of this
will be an apparent increase in the Teflon wall thickness. The Teflon element should be cleaned to
discourage this type of deposit from forming.
A second cause of this error is the release of dissolved gases from the water. This will only be a
problem on waters that are highly aerated. This causes the formation of tiny bubbles on the Teflon
and will cause an apparent depression of the reading. If this is suspected a sample of water should
be taken and left to stand for 24 hours to see if gas bubbles form on the container wall. A double
stilling well may reduce the problem by reducing the water exchange rate and thus dissolved gas in
the stilling well.
PVC SHROUD
DATAFLOW SYSTEMS LTD Page 9
www.Odysseydatarecording.com V 11/20
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