[Coral-List] Affordable conductivity sensors for several month deployment

[Jeremy J. Sofonia]

Hi Brittany 

You may want to check out the 'Odyssey' brand of loggers as they are relatively cost competitive:

http://odysseydatarecording.com/index.php?route=product/category&path=60

I've not used their conductivity / temperature loggers, however, have utilised their light loggers on past projects with success (although they required post-purchase calibration).

Keep in mind that biofouling can be a major issue for conductivity measures (sensor drift), so advise caution in your plans for 3-month deployment.  That is, you may need to visit them more frequently for cleaning to limit data loss (depending on local conditions).

Alternatively, you could go the other way and consider products such as the JFE Advantech 'Infinity - CTW ACTW-USB':

http://www.jfe-advantech.co.jp/eng/ocean/infinity/infinity-ctw.html

or the Seabird SeaCAT C-T Recorder (SBE 16plus V2):

http://www.seabird.com/products/spec_sheets/16plusdata.htm

Although considerably more expensive for these types of loggers, they have an integrated wiper system / anti-founand devices that facilitate longer-term deployments.  The sensors, calibration and components are also generally of a higher caliber.. more stable … more robust.

Upfront costs of theses units may be offset / justified by the reduced need for multiple field visits (e.g. vessel running costs) and/or simply the acquisition of valid data.

I often say, 'there are few things more expensive than bad data'.

Again though, much depends on your specific environment, logistical constraints and budget.  
I hope that this may be of of some help, 

--
Jeremy J. Sofonia M.Sc, B.Sc, CEnvP
Marine Scientist / Commercial Scientific Diver
Sofonia Pty Ltd
www.sofonia.com


On 29/05/2013, at 11:15 AM, Brittany Huntington <brittanyhuntington at gmail.com> wrote:

> Dear Coral Listers,
> 
> I am looking for advice to replace our current conductivity sensors (Onset
> Hobo Data Logger U24-002) with a comparable if not cheaper (<$700 per unit)
> option.
> 
> Onset has reported a programmatic error with the U24-002 and we are in the
> market for replacements.
> 
> Units will be deployed *in situ* for ~3mo. stretches in shallow (30ft)
> nearshore marine environments.  All suggestions appreciated.
> 
> Thanks in advance,
> Brittany
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