HM DigitalSP-P2 Replacement PH Sensor for PH-200

My original sensor head had accidentally been left in a cup of distilled water overnight. It was already getting some age on it, so leaving it in overnight caused quite a bit of the electrolyte in the sensor bulb to leach into the water. I noticed that my ph readings were taking forever to stabilize and when calibrating the number would be off by quite a bit prior to running the calibration. Anyway I ordered this replacement head and it got my meter back to full operation. The measurements were accurate and it was easy to calibrate. For A lower priced ph meter this brand is quite good. I use it in a greenhouse to sample ph as our plants grow. From that info I sometimes have to use special fertilizers to acidify the potting soil. If you have a ph meter from this company and think that your readings don’t seem correct you probably need a new sensor head. This will fix your problem. It is very easy to install.

I received my pen from Amazon with a dry probe as others have complained about. I soaked the probe in solution overnight, re-calibrated my pen & it worked fine for several months. I kept my pen wet at all times by storing it in a glass with a little solution from then on. However, in between grows, I didn't use the pen for a few weeks & the solution evaporated from my glass. After I allowed it to dry out, the pen would no longer hold calibration. So I ordered this replacement probe & it arrived in a sealed container, wet. Once I put it on, my pen calibrated without issue.I believe the pens arriving with a dry probe are fine because they pack it with a salt or something. Just soak it overnight & it will likely work fine, mine did despite arriving with a dry probe. But allowing the probe to dry out after initial use will cause an issue. Maybe HM Digital will see this post & shed some light on this.

This product worked for about 20 to 30 calibration before it went bad.The company was not real helpful.I don’t recommend it at all.It wasn’t a cheap meter,but preforms like one.JUNK dont BUY

The key to keeping these glass electrode pH sensors maintained is getting a 1L bottle of General Hydroponics (or equivalent) pH 7.0 calibration/storage solution and storing the glass tip in something OTHER than the provided case. It needs much more liquid than can fit in the topper with sponge. I use a small plastic Rubbermaid container with pH 7.0 liquid in the bottom. If you try and use the cap, the electrode is going to be useless (read: inaccurate) quickly.1) Calibrate to 7.0 before every usage2) Quickly rinse electrode in RO/DI/distilled water3) Dab dry, do NOT rub glass4) Measure solution in question5) Rinse electrode off in RO/DI/distilled water6) Return to container of choice filled with pH 7.0 calibration/storage solutionIf done properly, these actually get BETTER over time, to a point. When they come from the factory they don't have nearly enough of the solution around the electrode, so it takes awhile to return to normal. Personally I store my meter in about 25mL of General Hydroponics pH 7.0 calibration/storage solution, follow the above SOP every time I use it, and it's only been getting more accurate as time goes on.If you do not put the time into maintaining these, don't bother getting one. I work in a chemistry laboratory and the above SOP is how we treat all of our expensive analytical glass electrode pH meters that cost tens of thousands of dollars.

This is the second sensor for my PH200 Unit. I broke the glass sensor bulb on my last unit. I have had the meter for about three years now and its really durable and waterproof, however these sensors (like all PH sensors) are fragile and need care and maintenance.This unit is definitely a workhorse. I calibrate this about once a week with pH 7 calibration / buffer solution. I also calibrate with pH 4.01 and pH 10 solution monthly, and yes this does make a difference, in fact i had to calibrate this with pH 10 the first time since the reading was off by almost 1.What I especially like about this sensor, and the the respective meter, is it is accurate to 2 decimal points and displays it...so instead of just say a reading of '7.6' on other meters, this unit would read something like '7.67'. you get the idea, after all you are looking at a replacement sensor!

As others have stated, the product arrived drier than a salt lick. Okay... no worries... just rehydrate w/KCl.So... that's what I did!... 24 hours in KCl to rehydrate. After I rehydrated, I calibrated with Hanna 7.01 and also 4.01 buffer solutions and then overnight in KCl again. The verdict?... junk!I just checked the sensor and it reads 7.84 pH when it should be 7.01 pH! Who has the time to re-calibrate with every, single use?... no trust with this sensor at all.... and I am stuck because I own the pH meter! I will get another one... hopefully shipped in solution and functional.UPDATE... they shipped a second one very quickly. Thank you. HOWEVER... it was clear that they rehydrated before they shipped it... how do I know?... because the small contain that holds the sensor was wet inside! DUH!... most people--I would imagine--who order these are not stupid! Ha!The first thing I learned in Organic Chemistry Lab with regards to Ph meters is "IF IT DRIES, IT DIES".... they are shipping dead equipment!I'll give another update when I get the third one... until then... cheers!Update Feb 25th... I still have not received my third sensor... I sent the other two back already... waiting... NOTE the initial order was placed Jan 17th!... over a month ago and I still cannot check my pH.Update March 26th... After 5 sensors were sent to me, I have finally received one that works! Sheesh... over two months, and 5 sensors. Thank you to Amazon though for keeping the faith... it works!... of course after this amount of time and energy that I spent to receive a working product, it is no wonder this product receives a 1 star.Update April 3rd... it doesn't work!... held a pH for a day... now?... it doesn't even show a pH at all!... wtf?!!!!!!

Good replacement.

Falla igual que el original

First one lasted 5 years.Looking forward to another 5

I only opened this yesterday which is after the "return window" whatever that means. Everything seemed fine in the beginning and I was using it all day yesterday and then this morning I couldn't seem to calibrate it. The PH7 solution was reading 12 and the PH 4 solution was reading 8. I manually calibrated with the PH7 and then tried to use it but then the screen went blank. I removed the tip to find it full of water! I can only assume that my $100 pen is now useless and I need to order a new one. So I just lost out on $200.

Ordered 2 and they came today. I can verify they are indeed the right probe for the PH-200 but they both came dried out. I have attemped to rehydrate them both with solution but HM warns it is very bad for these probes to dry them out. The manufacture date on both was Oct 2012 and have clearly been sitting on a shelf for the last 5 years. Buy if you need but Be aware of the problem.