7.87 Inch Plastic Secchi Disk Set Secchi Disc with Black and White Quadrants, Steel Cone, Holding Line and 100 ft Tape Measure for Clarity Measurements

Bright color and balancing weight makes this easy to use

I was setting this up to use for the first time and the thin plastic disc broke when being dropped from 2 feet. We never even had a chance to get it into the water! Total garbage.

This worked well in lake water for about 10 uses, but now the tape rubs against the plastic holder and will not rewind smoothly.

This is a nice, relatively inexpensive Secchi disk for measuring water transparency in the environment. Historically, the 20-cm (7.87-inch) Secchi disk with black and white quadrants is used for limnological (lake), estuarine, and coastal ocean studies to measure water transparency; the open-ocean oceanographic Secchi disk is typically all white and 40 to 60 cm (15.7 to 23.6 inches) in diameter. This Secchi disk could be used in the open ocean but its characteristics should be noted on the data log sheet. While the 30-m (98-foot), non-stretching tape measure is not a bad idea (stretching and shrinkage of graduated Secchi disk lines can be a problem), I am concerned that the tape, which the vendor says is made of stainless steel (rather than fiberglass) may eventually corrode depending on the type of stainless steel, even if only used in freshwater. A better choice might be a depth gauge fiberglass tape. While it may not be on a reel, the line will not corrode, stretch, shrink, and being thinner in width, will have less drag in moving water which will keep the line more vertical in the water column.PROS• Nicely-made, relatively inexpensive, 20-cm Secchi disk for measuring the transparency of lake water in limnological studies as well as estuarine studies and coastal ocean studies.• The metal (stainless steel?) tape is good in that it will not shrink or stretch but it may be prone to corrosion, particularly in saltwater.• The conical weight (less drag) is good and the snap hook is a nice accessory; however, a stainless steel quicklink would be more secure than the snap hook.CONS• In addition to being prone to corrosion, the 12-mm (0.5-inch) wide tape will experience more drag in moving water and may not be vertical in the water column.• The tape does not appear to be threaded correctly on the reel (refer to photos). I believe the tape should run between the two red guides for a smoother feed.

The description says 100 foot measure, it's actually in meters. Wouldn't have ordered if I had realized. Otherwise, it is well made.