"Boomer" wrote in message ...
"So you can fix this meter by using 53mS calibration solution and
set 35ppt or 1.026 on the meter - whatever reading you prefer on
your daily routine."

53mS yes, Sg 1.026 no.The meter is trying to make a preset electronic conversion based on
NaCl.to the density or SG. They do not tell you which one it is. You would have to have a
seawater sample with a know SG of 1.026 then you could set it to Sg and the ppt would be
off

I am affraid you did not understand my point...

If you can properly calibrate the meter using 53mS Pinpoint solution
on a ppt setting to match 35ppt than with the same solution you can
calibrate it on the SG setting turning the screw to get 1.026 reading.

Is this correct or not ?

If it is, than you can calibrate the meter TO ONE SETTING and do not
switch it later. You just pick whatever unit your prefer in your routine.
One aquarist may prefer maitaining the tank to 35ppt, other to 1.025 :-)

"BTW - most reflectometers sold for this hobby have also the scale
calibrated to NaCl not sea water...

What is a reflectometer, there is no such thing :-).........refractometer.

Yes, BTW, you learned that from me, just like this meter

Why so important is it for you to point out a typo,
or from whom somebody learn something ?
Focus on the subject... please.

This is not a refract but a EC meter, big difference.

Not in this conversation subject.
We were discussing how insignificants are constant offsets
you can always subtract from the final reading...

Not all refract's are off just so you know.
The so called blue refracts, the most common in this hobby, happen to be right
on based on tests. Didn't know that did you ? That is because they are off from the
factory for a NaCl solution, which by luck ends up being right on to NSW.

The point is, that most of them (except blue one) show values
also calibrated for NaCl, and this does not stop aquarists
from using them... So what is the problem with this Digi Mate ?

"I would deem meter as useless if I would not be able to calibrate it.
If every measurement would read different, random value..."

That is something you won't know unless you test it.
Your logic makes about as much sense as saying you have
a pH meter and it can only be calibrated to work from 7.8-8.2 pH,
9 no deal, 6 no deal..... buy it anyway.

I do not understand above...
We read here that the meter is stable after calibration,
that it requires calibration about once a month, which
is reasonable. That readings are repeatable...
On top of it, a reef tank needs constant salinity, so
I do not care that the offset vary in a wide range of
the meter scale - I talk about using this meter for reef tank.

Knowing that it is calibrated to NaCl you can apply constant
offset to the reading, exactly as for the refractometer,
or calibrate it with 53mS Pinpoint solution TO ONE UNIT only
and stick with calibrated meter.
If you calibrate it to 35ppt using Pinpoint, and then measure
35ppt in your reef tank it will simply mean your reef tank
has proper water salinity.
If you measure less or more than 35ppt then you adjust salinity.

Do you agree with above ?

The offset is not constant throughout its scale.
EC meters do not use a constant scale
when converting the value uS to ppt or TDS.
The scaling is non-linear.

So we eliminate the problem by not switching between
SG and TDS - we stick with calibrated 35 ppt and within
close range around 35ppt (where the reef tank should be)
the offset will be constant.

The non-linear
scale being used is dependant on what TDS value you are using, NaCl, KCl, 442, Seawater,
alcohol, surgar, brix, etc. The meter would have to be set to a seawater scaling to
convert from uS to ppt. If the meter measured the value only in uS or mS there would be
no issue. That is why there is a company that makes a EC meter in uS, ppt, Sg for
seawater to the tune of almost $600. To do all of this correctly you need multipoint
calibration points.

You do not need this kind of meter for a reef tank.
You most likely use it with some laboratory environment...

When I buy some meter of any kind, for a function, I expect it to read what it should.

When I buy some cheap meter for a application I expect it to work withing application.
So if you assume you cannot get a better meter for $60 for a reef tank,
than what is this whole fuss about ? It works great for a reef tank!

For the price and what it gives and the issues it has yes, IMHO useless.
I could find a PinPoint for that price. The company could make
the corrections to this meter and for its cost would be a very nice meter.
I would want one.

How Pinpoint meter is better ?
And where you can get it new for $60 ?

Many people say SeaTests swing arms are also useless.......so are they.......

I like swing arms :-) I do not need anything better for a reef tank salinity.