Salinity Constantly dropping according to probe

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astralmind
Posts: 99
Joined: Fri Apr 01, 2011 10:53 am

Salinity Constantly dropping according to probe

Post by astralmind »

Weird one here.

According to the salinity probe I'm now at 32.5 ppt, extremely low for my reef (stable at 35ppt). I find this extremly odd as I've remotely turned off the ATO port and it still seems to be going down which makes no sense at all. Even with the ATO (which has been working flawlessly for the past few months) there should be little fluctuations on the salinity level and they should be temporary.

I decied to resume my ATO as it definitely isn't related to "over top off"

Any thoughts?
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: Salinity Constantly dropping according to probe

Post by rimai »

Things that can interfere with readings:
Air bubbles in the probe.
Algea growth in the probe.
Temperature (high dependent on temperature. if your temperature changes, so does salinity)
Corrosion on the BNC connector. I have to unplug and plug every now and then so that corrosion doesn't affect the readings. What we are measuring is the resistance of the water/salt in conducting electricity and the resistance is very small. Any type of corrosion can influence readings too. When I say corrosion, I don't mean what you can visually see. If it gets to that point, your readings would be totally wrong way before that happened. I'm talking about just a slight thin layer of corrosion in the probe contacts.
Roberto.
astralmind
Posts: 99
Joined: Fri Apr 01, 2011 10:53 am

Re: Salinity Constantly dropping according to probe

Post by astralmind »

Interesting. I'll definitely check it out when I get home tonight.

Could corrosion form as fast as 1 week of usage ? I just started using it a few days ago. Any specific ways to clean it?

Edit: Still dropping, now reading 32 by the time I get home I'll have fresh water :lol: Hopefully the probe is the issue not my waterlevel!
btorrenga
Posts: 100
Joined: Mon Apr 16, 2012 10:22 pm

Re: Salinity Constantly dropping according to probe

Post by btorrenga »

Interesting. My probe is reading 5.9ppt, which of course is not right. It seemed to start all of a sudden though. I tried recalibrating, but the calibration numbers sat at 0 (if I recall, I may not be recalling that correctly).
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: Salinity Constantly dropping according to probe

Post by rimai »

If the calibration number is at 0, the controller is probably not communicating with the module.
Roberto.
astralmind
Posts: 99
Joined: Fri Apr 01, 2011 10:53 am

Re: Salinity Constantly dropping according to probe

Post by astralmind »

I had a look at the probe and gave it a quick rinse in RO water and it still behaves erraticaly. My readings went as low as 32.1 and are now back at 34.1 while it should in theory read close to 35 - what it actually read initially. It might be related to my ATO interferring with the readings but the probe is placed before the ATO out.

I'll fiddle with it some more but I'm not sure what could be the issue.
pilonstar
Posts: 64
Joined: Tue Mar 20, 2012 2:56 am

Re: Salinity Constantly dropping according to probe

Post by pilonstar »

Mine too, I have calibrate with 35, all good till next day drops to 32 and in hours I have fresh water :o
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rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: Salinity Constantly dropping according to probe

Post by rimai »

If you move the cables around and push/pull them to make sure the connections are good, does it put it back to working condition?
Roberto.
javisaman
Posts: 63
Joined: Thu Jun 30, 2011 7:27 am

Re: Salinity Constantly dropping according to probe

Post by javisaman »

Having the same issues with mine. Probe no longer registers a value. There is corrosion on the contacts as well. Cables all seem fine.
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: Salinity Constantly dropping according to probe

Post by rimai »

Where is the corrosion?
Roberto.
javisaman
Posts: 63
Joined: Thu Jun 30, 2011 7:27 am

Re: Salinity Constantly dropping according to probe

Post by javisaman »

Let me get a picture. It's on the lines near the probe.
astralmind
Posts: 99
Joined: Fri Apr 01, 2011 10:53 am

Re: Salinity Constantly dropping according to probe

Post by astralmind »

No visible corosion on mine but it's been reading a flat 6 ppt non stop for the past few days. Will try and reboot. Could it be defective ? Pulling the cable around didn't change anything to the reading.
javisaman
Posts: 63
Joined: Thu Jun 30, 2011 7:27 am

Re: Salinity Constantly dropping according to probe

Post by javisaman »

6 ppm means it's not reading at all.
rimai
Posts: 12881
Joined: Fri Mar 18, 2011 6:47 pm

Re: Salinity Constantly dropping according to probe

Post by rimai »

Load this code:

Code: Select all

/**
 * I2CScanner.pde -- I2C bus scanner for Arduino
 *
 * 2009, Tod E. Kurt, http://todbot.com/blog/
 *
 */

#include "Wire.h"
extern "C" { 
#include "utility/twi.h"  // from Wire library, so we can do bus scanning
}

// Scan the I2C bus between addresses from_addr and to_addr.
// On each address, call the callback function with the address and result.
// If result==0, address was found, otherwise, address wasn't found
// (can use result to potentially get other status on the I2C bus, see twi.c)
// Assumes Wire.begin() has already been called
void scanI2CBus(byte from_addr, byte to_addr, 
void(*callback)(byte address, byte result) ) 
{
  byte rc;
  byte data = 0; // not used, just an address to feed to twi_writeTo()
  for( byte addr = from_addr; addr <= to_addr; addr++ ) {
    rc = twi_writeTo(addr, &data, 0, 1, true);
    callback( addr, rc );
  }
}

// Called when address is found in scanI2CBus()
// Feel free to change this as needed
// (like adding I2C comm code to figure out what kind of I2C device is there)
void scanFunc( byte addr, byte result ) {
  Serial.print("addr: ");
  Serial.print(addr,HEX);
  Serial.print( (result==0) ? " found!":"       ");
  Serial.print( (addr%4) ? "\t":"\n");
}


byte start_address = 1;
byte end_address = 128;

// standard Arduino setup()
void setup()
{
  Wire.begin();
  pinMode(7,OUTPUT);
  Serial.begin(57600);
  Serial.println("\nI2CScanner ready!");

  Serial.print("starting scanning of I2C bus from ");
  Serial.print(start_address,DEC);
  Serial.print(" to ");
  Serial.print(end_address,DEC);
  Serial.println("...");

  // start the scan, will call "scanFunc()" on result from each address
  scanI2CBus( start_address, end_address, scanFunc );

  Serial.println("\ndone");
}

// standard Arduino loop()
void loop() 
{
  // Nothing to do here, so we'll just blink the built-in LED
  digitalWrite(7,HIGH);
  delay(300);
  digitalWrite(7,LOW);
  delay(300);
}
Open Arduino
Go to menu Tools->Serial Monitor
Make sure you have 57600 baud
Reboot the controller
You will see the Serial Monitor window with stuff in it.
Copy and paste the results here.
Roberto.
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