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DO and Ph sensors — Parallax Forums

DO and Ph sensors

Brian CarpenterBrian Carpenter Posts: 728
edited 2013-05-18 10:28 in Accessories
I am looking for sensors that can be deployed in water for extended periods of time.. Any suggestions?

Comments

  • Tracy AllenTracy Allen Posts: 6,662
    edited 2013-05-13 22:28
    http://www.sensorex.com/products

    "in water" could mean lots of things, from DiH2O to creature from the black lagoon!
  • Brian CarpenterBrian Carpenter Posts: 728
    edited 2013-05-14 07:17
    Yes Tracy,
    I suppose that does leave it wide open. I need to monitor a fish pond but i want to do long term monitoring and not just the periodic Dip into the water with a handheld probe.
  • Tracy AllenTracy Allen Posts: 6,662
    edited 2013-05-14 12:19
    Not cheap. Algae and gunk degrade the response, so these sensors have relatively flat surfaces that allow for easier cleaning. They do require maintenance, and pH needs periodic calibration.
    process dissolved oxygen probes
    process pH sensors

    In a pond, galvanic isolation of the probe is pretty much essential. That is either done with an isolation amplifier/power for each sensor, or by making an arrangement with a pump to bring a sample of the water to an isolated container.
  • Brian CarpenterBrian Carpenter Posts: 728
    edited 2013-05-14 21:03
    Tracy,
    the actual application is for a fish hatchery tank. in your opinion, what do you see that i would need to monitor.
    I want to monitor Temp, DO, PH and flow rate. what else would be necessary.
  • Tracy AllenTracy Allen Posts: 6,662
    edited 2013-05-16 08:59
    Brian,
    I'm not very knowledgeable in that area. A friend here wants me to help him set up a closed system for tilapia that will involve input of worms from his ongoing vermiculture operation and output from both the worm casings and fish waste to fertilize the garden. Practically zero budget tho, so most materials will be scrounged. I think the first step is a solar powered pump and aeration system, but I don't know where he'll want to take it from there, in the way of monitoring pH and O2. There have been a number of threads here about aquaculture or at least aquariums.

    Quite a few years ago, even before I started working with the BASIC Stamp, I instrumenting a project for growing filimentatious algae, which were to be used for adding "spring" to corn starch based packaging peanuts. The setup was a a string of giant tomato semitrailer tubs, and also two clay-lined ponds. Someone before us had been trying to raise fish there. Water was circulated through this whole thing. It was a nightmare, because the water was shared with a nearby pear orchard, and several diversion valves that we did not control had to be in the correct position in order for us to get the water we needed to keep the tanks refreshed, and the whole site was way out in the sticks. One day a tracter (driven by someone named Murphy?), knocked down the power pole and knocked out the electricity and phone line (300 baud data modem) for a several days. Anyway, that is where I cut my teeth on the need for isolation of sensors that are in galvanic contact with bodies of water.
  • Tracy AllenTracy Allen Posts: 6,662
    edited 2013-05-18 10:28
    Hi Brian,

    I ran across this interesting article on fish farming from Purdue University extension service.
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