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Thread: Conductivity probe for Freshwater

  1. #1
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    Conductivity probe for Freshwater

    What should the reading be in a freshwater aquarium and what are the benefits to this reading?

    Kim

  2. #2
    Master Control Freak RussM's Avatar
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    Use of a conductivity probe in a FW system is not very common, it seems to me. A quick search found this:

    Freshwater

    When starting a new fresh water aquarium and before introducing fish, it is good practice to measure the water hardness value (GH) and evaluate if this value is suitable for the fish you are about to introduce. In other words, by knowing the GH value of our aquarium water, you can determine which species of fish will thrive in that type of water.

    In a newly established aquarium, conductivity will be roughly related to General Hardness (GH= sum of divalent ions, mainly Calcium and Magnesium) and TDS (Total Dissolved Solids) values: µS/cm x 0.5 = ppm TDS x 0.056 = dGH.

    Therefore, when buying a freshwater fish, it is very important to know the EC value the fish was living in, and which level will be needed to keep the fish healthy.

    For community freshwater tanks, the EC value may generally range from 100 to 300 µS/cm; Discus, Paracheirodon and other soft-water species require values below 100, while Cichlids from African lakes (Malawi e Tanganyika) thrive at values above 500 µS/cm.

    Once the most suitable conductivity range for your marine life has been determined, the best use of the conductivity meter in your filter is to monitor the changes in water conditions. Unwanted inorganic and organic pollutants, as well as fertilizers and other chemicals added to the water by the aquarium keeper, directly affect the EC value, generally by increasing it.

    In fact, every chemical, additive, piece of food, medication or conditioner you put into your tank affects the conductivity in your aquarium and the above mentioned "link" becomes less. Therefore, measuring conductivity is a way to continuously monitor the conditions of water, since a change in conductivity also indicates a change in water conditions. Any of these changes should be checked using a chemical analysis (test kit). Sometimes the easiest way to correct the EC value is to change the water, thereby reducing the concentration of pollutants.

    When starting up a new aquarium, get your water ready before you introduce the new species. Plan for a few days for the water to reach a constant temperature and the correct EC readings to be established. If the filter monitor is showing an EC value that is too high, the solution is to dilute the water with an appropriate amount of de-ionized (osmotic) water (a simple formula to calculate how to dilute water is: litres of water needed / actual dGH value x desired dGH value).
    E.g.: if your 80 liter tank has a GH value of 20 dGH and you want to reduce this value to 5 dGH the calculation is: 80 / 20 x 5 = 20 (liters of actual water) + 60 (de-ionized water) = 80 liters of 5 dGH water.
    Or, in other words, you need to replace 60 liters of your tank water with de-ionized water.

    On the contrary, if the filter monitor shows that the EC value is too low for the species (for example you want to put African cichlids in your aquarium) then you need to "harden" your water. This can be done by using some commercial salt mixes or solutions i.e calcium carbonate.
    Please do not send me PMs with technical questions or requesting assistance - use the forums for Apex help. PM me ONLY if the matter is of a private or personal nature. Thanks.

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    Thanks Russ, I bought this controller system to help me control the pumps, lighting and filters that I have. I love having planted fish aquariums and one day I would like to have a saltwater tank. I just wanted to know what these probes are used for and the proper way to use them. Years ago I had always wanted a apex setup and now I have one so every little git of help with it would be great! Thanks for responding!

    Kim

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    handimn1, did you ever get the conductivity probe to work for your freshwater aquarium? I run a zebrafish facility at a cancer institute and we recently had all of our "Profilux 2 Outdoor" monitoring systems fail with electrical problems causing melting at system outlet and pump plug connection. We have just purchased one of these systems to compare to our old systems. Everything except for the conductivity probe seems to work well for us thus far. Can you provide any help on how to calibrate it or any information you may have found? The info provided here doesn't really help me as it looks like a foreign language to me. I need it to sit at around 500-550 uS/cm or realistically in the range of 400-600 uS/cm. Of course we have an emergency acceptance of fluctuation between 300-1000 uS/cm in extreme cases like our monitoring system crash. If you can help or know someone who can can you please reply here. Thanks very much.

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    Quote Originally Posted by StewartLab View Post
    handimn1, did you ever get the conductivity probe to work for your freshwater aquarium? I run a zebrafish facility at a cancer institute and we recently had all of our "Profilux 2 Outdoor" monitoring systems fail with electrical problems causing melting at system outlet and pump plug connection. We have just purchased one of these systems to compare to our old systems. Everything except for the conductivity probe seems to work well for us thus far. Can you provide any help on how to calibrate it or any information you may have found? The info provided here doesn't really help me as it looks like a foreign language to me. I need it to sit at around 500-550 uS/cm or realistically in the range of 400-600 uS/cm. Of course we have an emergency acceptance of fluctuation between 300-1000 uS/cm in extreme cases like our monitoring system crash. If you can help or know someone who can can you please reply here. Thanks very much.
    I know this originally post is a few years old, but it is now 2018 and I have the exact same question for my Zebrafish facility. Did you ever find a solution to preciously measure in this range? 550-650 us/cm would be my range.

    Cheers!

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    Hello,
    I've learned from this thread, https://forum.neptunesystems.com/sho...for-Freshwater that the probe must be used with a PM2 module and not plugged into the head unit. Also, you can read in the thread (or from the PM2 user manual) what type of calibration fluid(s) must be used.

    As RussM mentioned in post #2, the value of measuring conductivity in freshwater is as a means of determining the buildup of dissolved components in the water. Some of these component (both solids and liquids) include organic pollutants, the result of metabolic processes. So in a way it can indicate when a water change should be performed. Other components will be items added to the tank, so in the case of a planted tank, the addition of fertilizer will immediately raise the conductivity because these are typically highly soluble salts, such as Potassium Nitrate and Potassium Phosphate.

    The unfortunate reality of conductivity measurement is that you cannot know exactly which components are responsible for which fraction of the conductivity rise, so for us freshwater users, it's more of a generic measurement, but which is still worthwhile.

    Unlike the data RussM quoted data regarding which species requires which values, I'm going to disagree with any of these hard limits. Freshwater fish really do not care too much about what the conductivity values are with the possible exception of breeding - and even that issue is suspect.

    The thing that is more important is the reason that the conductivity is outside the quoted values. If it's due to pollution then a water change is called for. If it's due to nutrient addition, for example, then there is no need for concern. The idea is not to fret over specific values but to learn and to monitor the weekly trends so that you know what is typical of your water supply and what is normal about the way your tank response to the various components that you are adding.

    Cheers,

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