salinity error?

[fwadiver]

My salinity reading seems wrong. when i calibrate the factor was approx 3100, when done it reads the 35ppt solution as 3.5, says tank is 3.0 now, is that in ppt? as well?

[rimai]

Sorry, can you rephrase?

[fwadiver]

ok 2 fold, salinity displays on my head units as 2.17ppt instead of 27.1ppt, also, according to my refractometer my salinity is closer to 31ppt than the 27 its reading, should i try to recalibrate, or can i tweak the setting manually?

[rimai]

I think it is your code that is placing the decimal point in the wrong place.
Can you post?
Your banner shows 27.
Make sure the calibration is in the same temperature as the tank.
1 degree makes a huge difference.
Conductivity is highly affected by temperature.

[fwadiver]

so like float the vial of calibration solution in the tank while doing the calibration?

Code: Select all

ReefAngel.LCD.DrawText(0,255,43,48,"Salinity");
      ConvertNumToString(text, ReefAngel.Params.Salinity, 100);
      ReefAngel.LCD.DrawLargeText(COLOR_LIMEGREEN, 255, 49, 58, text, Num8x8);
      pingSerial();

[rimai]

Yes, that would make them same temp

Code: Select all

ConvertNumToString(text, ReefAngel.Params.Salinity, 100);

The 100 is how much the parameter is being divided by. You need to change it to 10.

[rimai]

100 is for pH which has 2 decimal points

[fwadiver]

recalibrated on friday with heated solution, error seems greater now, currently my refractometer says 34ppt, reef angel says 26...

[rimai]

Here is what I'd like you to do.
1. Fill a cup with tank water
2. Place the probe inside
3. Calibrate using the cup of water.
4. Does it show 35ppt in the screen?
5. Leave the probe in there for a day or two. It should fluctuate a little as the temperature changes and evaporation occurs, but I just want to see what kind of readings you are getting.

[fwadiver]

Roberto,

did as you requested this morning, Calibrated and it did display the 35ppt this morning, probe is in a mason jar half full of tank water. Can you see the graph info from the portal or would you like me to post the reading info?

[rimai]

Leave it there to build up some history.

[fwadiver]

yup, plan is to leave it there until we get this figured out

[rimai]

Looks pretty stable in there now, huh?
You may be picking up interference somewhere.

[fwadiver]

looking at data over the weekend there were large swings in salinity on the hour every hour, dosing pumps maybe?

[rimai]

Nah, those swings were something that was messing up the readings. Do you see that when you moved the probe to the cup, the readings got stable?

[fwadiver]

yes but dosing the calcium and alkalinity salts was causing the reading to swing untill they dispersed through the tank, the dosing pumps and the probes are in the same area of the sump. Or do you think its electrical interference/noise? Dont have a scope here, its packed somewhere in my storage unit, I will try and dig it out and see if i cant use a 50ohm tap to read the sensor to look for noise

[fwadiver]

well stuck the probe back in my aquarium and it is going crazy again, any idea what to do to calm it down?

[rimai]

You must have some sort of stray voltage going on.

[fwadiver]

roberto i am not measuring any stray voltage in the tank at all, only other source i can think of is the ballasts for my light and the ph unit are kinda near eachother, I am going to try and move them to opposit sides of the tank and see what happens.

[fwadiver]

well found a small stray voltage 0.3VAC its only on the one side of the power strip and only between the common, the potential isint there with the safety ground blah! guess its time to go shutting everything down one at a time to see what it is.. or get a grounding probe.

[rimai]

Try removing the floats from the water

[fwadiver]

no floats, the thing that keeps bugging me is the ph seems fine, but salinity is still always up and down

[rimai]

I'm looking at your chart and it is so odd that it seems to follow a pattern.

[dazza1304]

Maybe a silly thought, but I had similar things that turned out to be my fault.

To minimise sockets, I used a shared a power supply for multiple expansion units, which caused interference.

Do you have separate power supplies for all you expansion units?

[fwadiver]

yes, the ones that need power supplies each has their own.

[fwadiver]

and now it seems to be stuck on 6ppt.....