salinity probe gone bad?

[bencollinz]

my salinity according to the probe has been spot on for the past 2 months but my corals were saying otherwise.

I bought the green milwaukee standalone, http://www.milwaukeetesters.com/MA887.html, to see if something wasn't clicking.

sure enough my sal was 36! should only be 33.

I recalibrated with 35 ppt solution but this time my number is only hitting 1079 instead of the 3000. Put the probe back in the tank and said my sal was ~140.00. Tested with the milwaukee and it's 33, just what it should be.

already did the put the probe in a glass of tank water, no difference.

anything else I can try? or is the probe dead?

and as you can see in my sig, it says the sal is 27.4 but it's really 33.

[rimai]

What do you get when you place the probe in the tank and go into calibration?

[bencollinz]

What do you get when you place the probe in the tank and go into calibration?

26XX

[rimai]

Your calibration fluid doesn't seem correct. 2600 is far from 1000.

[rimai]

May I ask why your point of view is that corals will not like 36ppt? And why you think that 33ppt is better for corals?
Do you have a fish only tank?
I understand fish prefer on the lower end, but corals actually do better in the higher end IMO.
There are many many references on the web that states that 34 to 36ppt is the target for a reef system.
Here is one of them: http://www.reefkeeping.com/issues/2007-03/rhf/
I think that between 34ppt and 36ppt is very acceptable. The important thing is to keep it constant.
The more swing you have, the more osmotic work corals will have to do to adapt to the swings, which isn't good ,but I don't think it hurts any to have a stable salinity in the higher end. In fact, you get more concentration of CA and ALK with more salt content, which is what corals use to build their skeletons.
There is even one company that states that all of our refractometers are wrong and report up to 1.5ppt lower... lol
http://reefbuilders.com/2010/03/30/dd-h ... -seawater/

[bencollinz]

Your calibration fluid doesn't seem correct. 2600 is far from 1000.

I tested the calibration fluid with my milwaukee, it's 35. I tested with a second brand new calibration fluid. same results. my milwaukee is calibrated with RO.

[bencollinz]

May I ask why your point of view is that corals will not like 36ppt? And why you think that 33ppt is better for corals?
Do you have a fish only tank?
I understand fish prefer on the lower end, but corals actually do better in the higher end IMO.
There are many many references on the web that states that 34 to 36ppt is the target for a reef system.
Here is one of them: http://www.reefkeeping.com/issues/2007-03/rhf/
I think that between 34ppt and 36ppt is very acceptable. The important thing is to keep it constant.
The more swing you have, the more osmotic work corals will have to do to adapt to the swings, which isn't good ,but I don't think it hurts any to have a stable salinity in the higher end. In fact, you get more concentration of CA and ALK with more salt content, which is what corals use to build their skeletons.
There is even one company that states that all of our refractometers are wrong and report up to 1.5ppt lower... lol
http://reefbuilders.com/2010/03/30/dd-h ... -seawater/

yes, my normal is 34. that's not the issue here.

by, "just what it should be", is at that very moment in time.

[bencollinz]

you can also see in my sig that it's reading ~32, but it's really 34 at this exact moment in time.

[rimai]

Yes, but the calibration solution is reading too low.
Are you sure it can be used for conductivity calibration?
The salinity probe is actually a conductivity meter not a salt content meter.
Try using tank water for calibration

[lnevo]

When it comes to calibration you want it to be as close the what your measuring. Using ro/di for calibration (which should be 0ppt) is going to be far from where you want and thus increase the amount of error introduced. Its the same thing with a refractometer..you could use ro/di but better to use 35ppt since then the amount of deviation to what your measuring will be less and this more accurate.

Theres a recipe online you can use with table salt to make 35ppt calibration fluid.

[bencollinz]

Yes, but the calibration solution is reading too low.

because there is something wrong with the probe. that's what I'm trying to get at.

if my standalone says BOTH calibration fluids are spot on 35 but the RA PROBE gives 3 different readings...

if you look in my code

Code: Select all

ReefAngel.SalMax=3000; // 35ppt

the first time I even set this thing up how long ago, the calibrate fluid STILL gave me 3000.

[bencollinz]

What do you get when you place the probe in the tank and go into calibration?

and you asked that above, but say this below...

Your calibration fluid doesn't seem correct. 2600 is far from 1000.

because the 2600 wasn't calibration, it was the tank in calibration mode. further showing something wrong with the probe.

[bencollinz]

When it comes to calibration you want it to be as close the what your measuring. Using ro/di for calibration (which should be 0ppt) is going to be far from where you want and thus increase the amount of error introduced. Its the same thing with a refractometer..you could use ro/di but better to use 35ppt since then the amount of deviation to what your measuring will be less and this more accurate.

Theres a recipe online you can use with table salt to make 35ppt calibration fluid.

this is per the manufacturer's directions. not me.

[rimai]

Did you try cleaning the probe?
Soak it in vinegar for a few hours to remove any calcium residue.
It almost look like you had air bubbles when you placed into your calibration fluid.
2600 in the tank seems fine to me, but 1000 in the cal fluid doesn't.

[bencollinz]

cleaning it right now.

what is the exact calibration fluid I need for the 'conductivity' probe?

[rimai]

All the ones I've used worked fine and I don't know if there is even one that doesn't work.
I just mentioned that because the reading you were getting (1000) didn't make sense when compared to the reading you were getting with tank water (2600) if they both were almost the same.
Just use tank water to calibrate.