I finally received my Hanna Instruments unit. It is a Model HI 9142.
I took some measurements around the pond earlier today and found pretty consistent readings of 7.4 - 7.5 mg/l. The booklet says the probe must be kept in motion? Anyways, I also took some readings in the flowing water of the stream on our property. I found the readings there to be only 4.4 mg/l.
The lower reading in the stream kind of surprised me because I know for a fact that it is loaded with Brook Trout. I would of thought that this moving water would have more oxygen in it?
Any thoughts on this?
If it's a Hanna that is good quality and made in Italy. You're good there.
As far as it saying, "the probe must be kept in motion" , it simply means while it's taking a reading you move it back forth about 1 foot per second. You'll get a higher reading that way.
That does seem odd the reading is so low in the stream. Do you calibrate your meter every time you turn it on? Or if the temp was significantly lower in the stream vs. the pond perhaps you needed to wait until the meter adjusted? I assume the probe tip is kept in a moist receptacle? It didn't fall out and dry up?
The only other explanation would be there is something odd going on in the stream, like serious organic matter being washed in from flooding that is using up oxygen.
