Welcome to EnviroDIY, a community for do-it-yourself environmental science and monitoring. EnviroDIY is part of WikiWatershed, an initiative of Stroud Water Research Center designed to help people advance knowledge and stewardship of fresh water.
New to EnviroDIY? Start here

Reply To: Depth measurement using MaxSonar

Home Forums Mayfly Data Logger Depth measurement using MaxSonar Reply To: Depth measurement using MaxSonar


    I look at the measurement accuracy, and vented depth sensors. Especially at lower water levels vented depth sensors are I believe the most accurate.
    Good measurement accuracy starts at about 0.25% of range and optionally can be of 0.1%
    I’ve been using the Keller Acculevel for ranges over 10′, and characterizing the Keller Nanolevel for ranges under 10′ – both of these use a Modbus interface – RS485 physical driver and excitation voltage of about 12V.
    The accuracy including temperature compensation can be selected to be 0.1% – ie for 10’range is +/-0.01′(+/3mm) – across temperature variations. That is if you have a smaller temperature range the accuracy can be better than 0.1%

    https://www.instrumart.com/products/33962/keller-acculevel-submersible-level-transmitter (Start ~$527)
    However if accuracy is important, you have to dig a bit deeper in to the specification, I can explain if interested.
    The do have a Keller Digilevel SDI-12 which has the same spec – but haven’t seen anybody interface to it. Shouldn’t be too hard I would think, but there isn’t much value to their SDI-12 as it still requires 6V excitation.

    and the Keller Level range

    We initially used the Keller LevelGage sensors, but in streams, they started failing after a couple of years and where replaced by Acculevel then Insitu LT500.
    The hydrologists I work with have good experience with Insitu LT500 series for accuracy (0.1%FS and 0.01%FS) and stability. They are expensive (base $2K+) and are standalone, they have battery and loggers, the cables are highly engineered devices and cables. Recently I’ve had two of the pig-tail connectors fail (at$350each). There isn’t a ModularSensors library for them yet.

    I’ve blogged about accuracy on sensors (but not specifically the Keller AccuLevel).

    Comparison temperature dependency: LT500, Keller Nano Level

    I recently got a quote for the CTD-10 (10m or 30′ – they only do the 10m now) with a fixed accuracy at 20C of 0.05% Full Scale or +-/5mm and no statement of how it varies with temperature (called temperature compensation).
    UpdateJan9th: I got a reply from leo.rivera@metergroup.com “We typically evaluate this from 0 to 50C and we see somewhere around +/- 2 cm in that range. It does vary sensor-to-sensor and some sensors have lower sensitivity.”
    So practically they are saying temperature compensation is challenging, and they could have the readings varied by ±25mm or 0.25% of scale – and they wouldn’t take the instrument back.
    https://www.metergroup.com/environment/products/hydros-21-water-level-monitoring/ Quote $491 per sensor and with a 10-meter cable.
    The CTD-10’s value seems to be its widely used in ModularSensors, and can be interfaced to simply with the base Mayfly, though I don’t have any experience with it.

    Hope that’s useful, and not too much info!! There are a few people using Acculevels, so if you have any other questions, maybe you can describe the expected site and also the accuracy you are aiming for 🙂