HM DigitalCOM-100 Waterproof EC/TDS/Temp Meter

Quick summary first and full review below:Positives:Rugged designWaterproof and dust proofBatteries and lanyard includedDifferent measurement optionsCalibration optionInstructions in clear EnglishGives quick, reliable readingsReplaceable sensor (although not readily/cheaply available in UK)Negatives:Screen not very large and not illuminatedInstructions in small printSlightly more complicated than simple TDS meter, due to different measurement unit options (although latter is also a plus)I had previously bought a cheap TDS meter, but decided to get something a bit more reliable, as the electrodes don't last forever, anyway. I use it for plant nutrient solutions, but it would work for any liquid application. It displays as TDS in ppm or ppt (at 2 different conversion rates), mS or micro-siemens. Generally, in hydroponics, what's referred to as EC is measured in mS, or if you multiply that by 10, you get the CF value. In case you don't know (I didn't before): TDS meters measure electrical conductivity (EC) and convert that value to TDS, for which there are different conversion rates. You can look up the conversion rates in tables online. This also provides a temperature reading in C or F and automatically compensates for temperature (which otherwise affects the reading). I've not calibrated it yet, so can't say for sure how accurate it is, but am confident it's more than accurate enough for everyday purposes and readings remain the same for multiple measurements. I looked at the Essentials EC meter (only 1 review, but their ph meter has many good reviews), at a slightly lower price, and providing similar specs, but with this one, you can replace just the sensor, which you can't with the Essentials meter. However, the replacement sensor does not seem to be widely available. After a bit of searching, I found out the part # for the sensor: if you search google for "HM Digital SP-C1", you will get some results. Cheapest I saw was on ebay, sent from US, for about £25 with international tracked delivery. This is more than sturdy enough for everyday use, and has an IP67 rating (dust and waterproof for immersion up to 1 meter, though not hermetically sealed). Instructions are in clear English, easy to understand, but the writing is small. It comes in a box with plastic insert, with a ribbon lanyard that fixes to the top and AAA batteries. Measurements stabilise very quickly. The screen is not huge, and displays multiple values, but is easy enough to read with normal eye sight in good light. There's no backlight, which would have been a nice feature for poor lighting situations. Overall, am pleased with it for the price, and would recommend.

If, like me, you have been scrolling and scrolling and scrolling through pages of Chinese rubbish, looking for a decent product that is going to last years and offer accurate results then I cannot recommend this product enough. It is well built, ironically, waterproof considering it is testing water… Yes, 95% of the others don’t! it is brilliant and very accurate and I highly recommend it.

The meter arrived in good time and in good condition. I bought this meter to check water quality of a well. As a simple test, I compared the reading to that stated on a bottle of well-known mineral water and was gratified to see that the values correlated well. This was based on factory calibration - I didn't calibrate the meter myself.I am happy with the physical properties of the meter, it is sturdy, waterproof and has worked as described in the supporting literature. I would suggest that you read around the web as to the exact meaning/implications of the readings the meter gives in the context of your own requirements, I found the information I encountered most informative and useful...

This is an excellent piece of kit that I use for drinking water measurements and hydroponics media making. It might be more expensive than other cheapo ones, but it is nice knowing this is super accurate (especially if you calibrate it to cater to whatever you are using it for). I figured I was probably going to buy just one of these TDS meters in my life, so why not just get the best and keep it for life. I can also just change the electrodes in the future if it needs it but from reading the instructions, I probably won't ever have to unless I start a hydroponic farm! The other thing I like about it is that it is waterproof - it feels strange enough dipping something with an electronic display into a solution so not worrying about whether it will be damaged or not and “how far am I dipping it in?” is a real bonus. If you need to monitor EC or TDS of solutions on a regular basis, then this is highly recommended - make sure you have a source of purified (reverse osmosis or de-ionised) water to wash the tip between uses and before storage to make sure that it does indeed last a life time!

Solid design, variety of unit measurements which helps if you need ppm or ec.

I wasted a lot of money on cheap rubbish units before finding the HM Digital COM-100. This unit seems well made, the buttons are easy to use (although I'm not sure why they are offset to the right) and the screen is large and easy to read. I check the calibration with EC calibration fluid regularly and find the meter to be accurate to plus or minus three percent. This accuracy is fine for mixing up plant nutrients and I've not come across anything more accurate for this price

This meter works fine when it works... I have to replace the batteries after only 3 uses and I always switch it of to save battery power! This is very annoying and should for a device so expensive I had expected it lo last a lot longer on the batteries provided! I use it for my shrimp tanks to measure the conductivity. The devise as such is a sturdy product and seems to be accurate

Well build. Accurate, repeatable measurements with accurate indication of temperature. Waterproof.Mode ppm with conversion factor NaCl works best for me. (1 ppm = 1mg/L so 5000ppm = 5 grams / liter)Mains water at my home measures 204 ppm and my favorite bottled water (suitable for babies) 23 ppm.

Much more accurate that cheap TDS meters. Temp stable. Using it for RO water and CS. Worth the price

My aquarium runs on 7GH and 2KH, this meter reads 400+TDS, my cheap ones all read 200-250, there is no way with those parameters im at 400+ TDS with weekly water changes. For that price an absolute junk item, very dissapointed.

I have been using for three months no problem at all.

Es practico y preciso me agrada que es a prueba de salpicaduras y la calidad del equipo es buena

JUSTE PARFAIT