Reddit reviews HM Digital TDS-EZ Water Quality TDS Tester, 0-9990 ppm Measurement Range, 1 ppm Resolution, 3% Readout Accuracy

Like most super powers, you can buy it for under $20

https://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

*first result I got on amazon. I'm not sure how good it is.

I have the same one. TDS meter reads in single digits.

Honestly, you can do much better for your money... There are kits in the Starter Shopping Lists to the right on the sidebar.

I was wondering the other day what exactly I would need for a turn-key grow setup, and put the following together. Mind you, this is not TOP of the line shit, but it will absolutely get you into the hobby!

600W Tube / Timer / MH & HPS Bulbs / Hangars / Ballast - $157.50

6 Inch Carbon Filter / 440CFM Fan - $149.75

25 Ft. 6 Inch Ducting - $19.10

48 x 48 x 78 Tent - $139.99

FFOF - $18.99

General Hydroponics Go Box Starter Kit - $35.95

CALIBER IV DIGITAL HYGROMETER - $19.23

Smart Pot Container - Pack of Five - $20.65

Micro-Tip Pruning Snip - $10.19

Light Duty Soft Wire Tie - $7.84

PH & Temperature Meter - $79.95

Water Quality TDS Tester - $15.59

LED Handheld Microscope - $16.81

Total just under 700$ and you are getting a LOT more for your money.

Don't blindly take that list, shop around, deal hunt, and do the research! There are many hidden costs associated with growing ><

It measures the total dissolved solids in the water, which for the most part is what matters, buy one, stick it in the water. If it reads under 50ppm it's fine. If it's over it's no good.
Linky

To be fair, tap water commonly has some ions in it - some salt, some rust. Which makes it conductive. Depending on a lake it can be less conductive than tap water. But that "depending" is pretty much the key. Unless you bring solid particle tester with you everywhere - you can't be sure.

Id rather use hard water than soft water. Too much salt buildup kills plants.

Take a sample to your local fish store if possible (Or purchase a PPM/PH meter) to find out your PPM and PH.

Anything above 300ppm gets a little sketchy and you will want an RO system.

PH can be altered but anything over a PH of 9 you will be using a ton of PH down.

If your PH and PPM are both below what I stated above I would still recommend something like a Small Boy filter for Chlorine/Chloramine and undissolved particles.

>With the raft, don't the roots sit in water?

 

Yes and no. What you want to do is get enough foam so that about half of inch sits outside the water at all time. This allows the roots to breath outside of the water (like the DWC). Again, don’t let this part get dry or it can cause air pruning. You can do this by allowing the net pot to sit a little higher in the foam, planting higher in the net pot, or getting a little thicker foam.

 

I am attaching a link to MPH Gardener. I would say look over his stuff. He is pretty freakin’ awsome.

 

https://www.youtube.com/watch?v=oDYeffYcVkY

 

>Can you recommend all the testing equipment I need or provide an Amazon link?

 

You will need a PPM and pH meter. These are two cheap version I use. You can go as crazy as you want, just remember the cheaper the more you replace them.

 

pH: http://www.amazon.com/Etekcity%C2%AE-Accuracy-Measurement-Resolution-Handheld/dp/B00FJFEB2O/ref=sr_1_1?ie=UTF8&qid=1427150876&sr=8-1&keywords=ph+meter

 

pH Callibration Liquid: http://www.amazon.com/gp/product/B007X5KAV4/ref=pd_lpo_sbs_dp_ss_2?pf_rd_p=1944687462&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B004HE7W42&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=118RAVZJW5YGE1CB5EE9

 

PPM: http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_3?ie=UTF8&qid=1427150876&sr=8-3&keywords=ph+meter

 

>With lettuce greens, I think the raft would work. Perhaps I'll do DWC with tomatoes; I think it would be hard with greens.

 

That sounds great. Watch the MPH Gardener on his Dutch bucket tomatoes first. I will preface with he does use MiracleGro for his nutrients, which is a highly debated topic. So take the nutrients with a grain of salt.

 

>How do you swap out water? Do you just do a 100% water change? Is that cost-effective with the price of nutrients?

 

I do do a 100% water change every two weeks. You can check the level of nutrients and try adding them; however, I have an outside garden during the summer and just put the nutrients there which does wonders for them.

 

Also, it gives me a chance to add in bacteria as I need it.

 

There are methods for balancing the pH, nutrients, and keeping the same water; however, as a beginner I would not get into this. If you want to we can talk but just swap the nutrients out as you go.

 

And this is where I will highlight that you want a shallow reservoir because you want to keep the minimum water you need to not to waste nutrients. I would say go to a hardware store and ikea and see what bins will work.

 

>Do I need to paint my plastic bin black to deter mold growth? Thanks so much for your help!

 

Yes and no. There are ways to go around managing algae with either pond products or barley straw mats, but to be honest sealing off holes and painting things black is the easiest.

 

Keep in mind that if you are going to have high heat in the room a white reservoir might be better than black.

I run a DWC and use this for a PPM meter. Does the job. Feel free to PM me if you have any questions or want to chat.

It's just as possible that your tap water has too many minerals. My tap water supply can sometimes have 6-9 times the optimal level. Short of having a full water test done, you can buy a cheap TDS meter off amazon (we use these) but I'm sure any of them are fine. You're looking for an target of about 150ppm but I've had great cups from 100-350ish. You might find it might be a good idea to mix some distilled and tap, preferably filtered if your water has any distinct taste to it.

For no cost (aside from coffee and water) you could just try a 10%tap 90%distilled batch, a 50/50 batch, and a 100% tap batch and just make some adjustments from whichever you like the most.

Well those roots look healthy to me. Just try the flushing. Here is a TDS I use for $16. Even if you do not go for the calibration solution gotta have it if you want to grow the dro.

After you transplant leave your light off for 24 hours to help with the shock. Sometimes hydro shops have used bulbs they will sell for cheap, depending on your ballast your should be able to run a 250 watt bulb if that's all you can find and afford. If the plants aren't in cubes I suggest letting the roots stay in the small clump of soil around them. You could wash the roots off but it will stress them more and when exposing them to lights you risk killing the roots. After you transplant fill right up to the bottom of the leaves that are growing. If you don't have a ph meter I suggest something like this. http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_1?ie=UTF8&qid=1396007211&sr=8-1&keywords=ph+meter Its fairly inexpensive and very easy to use. If all you have is less than $30 to spend I suggest the meter over a mh bulb and pick up a thermometer. Also since the plants will be in shock once you transplant them foiler feed with water (spray down the tops and bottoms of the leaves with clean soft water)

I'd make a tea from the soil your not using. Its not going to be the best but will give you some nutes if you can't afford to pick up bottles.

Grab a TDS meter and see what the water looks like. https://www.amazon.com/dp/B002C0A7ZY/ref=cm_sw_r_cp_awdb_t1_hi.xDbFM7VJRA

RO/DI water is great to use!

I have this one, works well for me and apparnetly measures 0-9990 ppm.

They can also be referred to as total dissolved solids or TDS. You can purchase a TDS/TSS meter to measure that, but you should do some research first to understand what you're measuring and what your TDS is in your water source.

If you want shrimp for algae control, look at amano shrimp, which are usually large enough to fend for themselves when housed with a betta. In a 5 gal, one would certainly do the trick.

Yeah I didn't go into it expecting much (an ounce or two) so we'll see what it comes out too, i'll be happy to get that.

Here are the links for the meters I get. I tested the ph meter and compared it to drops and it is spot on. Not sure about the ppm one but it got good reviews.

PPM Meter

PH Meter

Thanks for checking out my grow!

Thanks for the shoutout! Glad I could be of some help!

Ok, so let's get started.

First, what part of Texas are you in? I believe you have native CP's closer to the eastern part of the state.

Now to answer your questions:

1. Here's a summary of CP expert Barry Rice's trip to eastern Texas. It has various CPs listed. I'm not certain about non-CP Texas natives.
   
   
2. I use this brand of Sphagnum Peat Moss exclusively. It's higher quality than many other brands. It also expands to about 4cu ft from what I understand.
   As far as the next ingredient, I go with Silica Sand which is also called pool filter sand. Do not use play sand, paver sand, etc. only Silica Sand/ Pool Filter sand. This is the brand that I use. I've hear Quikrete makes some, but it's not available in my area. I typically do a 50/50 or 60/40 mix. If your area is fairly dry, I'd probably do a 60 Sphagnum/ 40 Sand mix. You can add perlite if you'd like, but I'm not sure it's necessary. Other optional additions are long pine needles and long fiber sphagnum top layer. Long fiber sphagnum as a top layer would be good if your climate is fairly dry as it will supplement the plants with some humidity.
   
   
3. When you say large mini-bog, are you meaning that you want to keep it in a container like I have, or do you actually want to build it in ground? As far as in ground, I'm really not experienced with this. As far as water goes, get yourself a rain barrel. Make sure you test it with a TDS meter before using it (should be under 45 or so PPM). 1 inch of rain on a 1000 sq/ft roof will yield around 600 gallons. You can often make a rain barrel easily from a food-grade 55 gallon drum. Just check your local craigslist and you can pick them up for around $10-$20 and there are many guides on how to transform them for around another $20. These will cut down greatly on water costs. If you get fancy with it, you could possibly hook up a drip irrigation system that would be buried in the bog and water could release from the rain barrel with a hose valve timer. This would water from underneath and would simulate their natural habitat.

http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

I would think it would give you a basic idea of quality.

$15.37 HM Digital TDS-EZ Water Quality TDS Tester, 0-9990 ppm Measurement Range , 1 ppm Resolution, +/- 3% Readout Accuracy

https://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_3?ie=UTF8&qid=1503463109&sr=8-3&keywords=water+testing+meter

It is possible that you could have pretty decent tap water. Your best bet would be to get a TDS meter to determine the amount of total dissolved solids. Preferably you would want less than 5ppm.

People have successfully kept saltwater aquariums without RO/DI, but using RO/DI water limits the chance of any nuisance algae and poor water quality as some tap water already has ammonia/nitrite/nitrate in it. I would recommend using RO/DI water, but if you don't want to have to buy a unit - you could always buy RO/DI water from your local fish store. It's usually ~$1 per gallon. I would advise against any prepackaged "Natural Sea Water" though... which is like $15 for 4 gallons, so you'll know the difference.

Alright taking into consideration the 12 plant limit here, my previous setup was too big for so few plants. So with some downsizing hopefully saves even more!

Tent - GROWNEER 48"x36"x72" Lodge Propagation Tent

Lights - HLG65 lm301b and red 660nm hydroponic grow light 4000K x 2

Kingbrite 240W samsung lm301h 288v3 quantum board X1

Fan - AC Infinity CLOUDLINE S4, Quiet 4” Inline Duct Fan with Speed Controller

PH Meter - Wellcows Digital PH Meter

PPM Meter - HM Digital TDS-EZ Water Quality TDS Tester

Carbon Filter - VIVOSUN 4 Inch Air Carbon Filter

Ducting - VIVOSUN 2-PACK 4 Inch 8 Feet Non-Insulated Flex Air Aluminum Ducting

Nutrients - MEGA Crop (2500g)

Botanicare CAL-MAG Plus Plant Supplement 2-0-0 Formula, 1 Quart

PH Control - General Hydroponics pH Control Kit

Soil - PREMIER HORTICULTURE 20380RG PRO-Mix HP High Porosity Grower Mix

Pots - Gardzen 10-Pack 1 Gallon Grow Bags x 2

Cloning Machine - CLONE KING 25

Total - 880.62 (includes shipping)

So with this setup ill keep 1 or 2 mother plants and then run the rest in SoG in 1 gallon pots. Using the 2 4000k lights for the mother plant and the cloning station and the 240w for the SoG area of the tent. Its a small setup but I think it'll work. Any idea what kinds of yeilds this could achieve? Any further input would be greatly appreciated.

I got the pH meter above, and this TDS meter, whilst my cabinet is monitored inside and at exhaust exit with this temp/humidity gauge with min/max for all fields.

Combined price is < $60.

Seems to work just fine.

But I do like the gizmo you linked to. Maybe for a hydro setup?

You should consider buying a TDS meter like this one. It allows you to accurately keep track of the solution strength.

Don't worry about buying a more expensive one, you won't need much for a home project.

Would this work out?
http://www.amazon.com/gp/aw/d/B002C0A7ZY/ref=mp_s_a_1_1?qid=1414341438&sr=8-1&pi=SY200_QL40

Or this one?
http://mobile.walmart.com/ip/19582190?wmlspartner=wlpa&adid=22222222228015536541&wl0=&wl1=g&wl2=m&wl3=40872537152&wl4=&wl5=pla&wl6=78764899592&veh=sem

I'm not really sure what scale tbh, here is a link to the pen I got on Amazon if that helps at all. It might appear a lot lighter than it actually is due to my light in the tent being so bright white. Here are some pics with the tent light off and my phone flash on. I'm not sure if that's the right shade of green or not. I just watered them again after reading some info online with recommendations on Coco watering. I adjusted it to have some calmag in it and increased the Flora Grow and lowered the Flora Micro. Had a ppm of about 580 this time. Hoping it will make them happier.

These are what I use. They work just fine.

pH:

http://www.amazon.com/Milwaukee-Instruments-pH600AQ-Tester-Calibration/dp/B005H78ZI0/ref=sr_1_1?ie=UTF8&qid=1348464821&sr=8-1&keywords=milwaukee+ph+test


TDS/EC:

http://www.amazon.com/HM-Digital-TDS-EZ-Auto-off-Function/dp/B002C0A7ZY/ref=sr_1_6?ie=UTF8&qid=1348464821&sr=8-6&keywords=milwaukee+ph+test

Here. It is by no means a "lab grade" device but gives great reference readings when analyzing how much your plant is eating (for my DWC setup anyways). I've never grown in soil but see people run a sort of "reference flush" to compare their previous runoff from the last time they watered to judge if their plants are consuming more nutes or more water so they can adjust their amendments accordingly. I do the same sort of thing on my hempy buckets but it is just so much easier since my medium is inert.

with a PPM meter.

http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_1?ie=UTF8&qid=1383252628&sr=8-1&keywords=ppm+meters

I edited it in. This one.

I think you should be fine using the maxigrow and cal-mag for now. I would not recommend using the rockdust or azomite though. You should get all you need in the maxigrow for now.

As for the TDS tester, I use this one It is cheap and works fine. It converts the PPM to EC by dividing the reading by 500. For example... 750PPM is going to give you a 1.5 EC. Some TDS testers in other countries will use a different conversion rate to get you the correct EC. EC is universal.

So lets say your peppers need to be at a EC from 1.3 - 1.8 "depending on the size." With the TDS meter I sent a link to, you would want your water to be at 650 PPM to 900 PPM. If your tap water is coming out of the tap already with a bunch of minerals already in it like 300 PPM worth, then you want to add your cal-mag and Maxigro until you hit that 650 to 900 PPM range.

As for your pH, you want to keep it as close to 6 as possible for peppers.

When it was first introduced I wondered about the connected version. Couldn't see the difference between buttons on the brewer vs buttons on your phone. The fact that the price is lowered seems to substantiate my opinion. It's a "gee whiz look at what I can do" feature regardless of whether the feature makes any sense.

As far as water quality there's a difference between hardness (measured in grains) vs total dissolved solids per whatever(tds). There are kits to measure only hardness, but I think this device will tell you more about your water: https://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

The common wisdom seems to be not to use softened water as it will not extract the tastes from the coffee properly. Rather, filter out the tds.

I use a Zerofilter, and Brita filtered water to bring the tds up to 75-100 or so which is the level I think I saw Behmor recommend at one point somewhere.

Hey, I'm looking at amazing water test kits now -- what exactly should I be testing for? pH? something like this?

or this maybe?

I am using this device:
http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_1?ie=UTF8&qid=1452279486&sr=8-1&keywords=water+quality+tester

I used this device on :

1. Water tap : 50 PPT
   
   
2. Filtered water gallons that I filled in one of these machines in safeways : 7 PPT
   
   
3. Brita water filter: 80 PPT
   
   
   To answer your question:
   
   
4. The filter is 1 week old. ( I did follow the steps of empying 3 full loads before start using it).
   
   
5. ?
   
   
6. Yes, that is possible
   

the Bluelabs gear is nice if you have the money.

I bought a simple $15 PH600 on amazon

http://www.amazon.com/Milwaukee-Instruments-PH600AQ-Tester-Calibration/dp/B005H78ZI0/ref=sr_1_1?s=lawn-garden&ie=UTF8&qid=1334068927&sr=1-1

and just as cheap a TDS meter

http://www.amazon.com/HM-Digital-TDS-EZ-Tester-Purity/dp/B002C0A7ZY/ref=sr_1_2?ie=UTF8&qid=1334068952&sr=8-2

both work incredibly well

Posting the same thing I did in /r/Plano on this since all of our water around here comes from NTMWD (Which has a purification plant in Wylie). While some may argue we're "within acceptable standards" I've always said on here when this comes up year after year when the lakes turn over and they load the water with chlorine there should be more science on what is acceptable for drinking water. Before that it smelled like swamp water when the lakes turned over, and this is like choosing between the lesser of two evils, I know. Would you rather drink bacteria or chlorine? I don't want to drink either, and that's why I bought a reverse osmosis filter.

Just like in recent history more science lead to the removal of lead in gasoline and paint. I personally don't drink the local water without reverse osmosis, filtering it first because I don't like the idea of putting "trace amounts" of carcinogens in mine or my kids bodies because some agency says the levels are "acceptable" and when very little information on what scientific studies were done for them to come up with what is "acceptable".

It also doesn't dispute the fact that our area has some of the highest concentration of PPM crap in our water than most of the nation. If you don't believe me buy a PPM pen off amazon (https://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY) and test your water. Compare to the rest of the US: https://www.h2odistributors.com/pages/info/hard-water-map.asp My tap water usually tests between 300-350 PPM. That's beyond red for that water redness map there and doesn't accurately reflect what our area tests.

If more science comes up with a warning that we should probably be reverse osmosis filtering our water before drinking until they can fix the supply problem, I'm fine with that. At least the information is out there for us. If not, I guess maybe when people die early from some form of cancer because they thought people like me were crackpot conspiracy theorists arguing on what is "acceptable", I guess that's just Darwinism in action.

Make no mistake, there probably won't be an easy long term fix. There are massive differences in how we treat water here compared to other states. For example on how corners are cut here, compare what they have in California for their intake, a cement lined reservoir:
https://en.wikipedia.org/wiki/Silver_Lake_Reservoir

To ours, a dirt reservoir:
https://en.wikipedia.org/wiki/Lavon_Lake

Dirt brings algae and bacteria and drives TDS up. You have to treat that with Chlorine and other chemicals.

Just my 2 cents on why I drink RO water living here.

Aside from a good filtering setup, a cheap TDS tester like http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ will tell you if there's any increase in stuff in your water. You can measure your baseline for a while and if there's ever a perceptible change, you can test again. It won't tell you definitively what's dissolved in the water, but it can help you check.

HM Digital (brand) TDS meter with 342 ppm calibration solution for it. On the back it has to have "Calibrate with NaCl" screw. This one was available locally.

Tds tester from amazon

HM Digital TDS-EZ Water Quality TDS Tester, 0-9990 ppm Measurement Range , 1 ppm Resolution, +/- 3% Readout Accuracy https://www.amazon.com/dp/B002C0A7ZY/ref=cm_sw_r_cp_api_YGc-ybYV4Q0QV

Yeah def. grab one of these off amazon they are super cheap and usefull. https://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

Works great.

Mine is HM Digital, with 342 ppm calibrating solution from them.

Any would work, if it has "Calibrate with NaCl" on the back.

>Where would one get such a meter?

This is the one I bought.
HM Digital TDS-EZ Water Quality TDS Tester, 0-9990 ppm Measurement Range , 1 ppm Resolution, +/- 3% Readout Accuracy https://www.amazon.com/dp/B002C0A7ZY/ref=cm_sw_r_cp_apa_dqfrzbBA5R7QJ

You will want this. Tap water you say? That is the likely culprit. So you will need this, and this. After this your troubles should be gone.

No one has mentioned it so I will:

Get a Parts Per Million meter. It doesn't have to be a fancy one, and actually see what's going on. My water tastes and smells pretty bad, but is only around 170ppm total dissolved solids. If I simply let it sit in a jug overnight, it tastes way better because the chlorine evaporates.

Also, request an analysis from your local water company. In my state, they are required by law to send one annually. It's a list of every molecule in their sample, but with Flint demonstrating, the testers may "pre-flush" the pipes before taking a sample, so if you don't trust the municipality or private water works, you can get your own sample relatively cheap (Home Depot does them for free where I am).

All in all a reverse osmosis system, or even just a passive charcoal one, should help tons. The former can actually take out chemically bonded impurities, while the later removes suspended particulate.

I add 3 tablespoons per gallon or 12ml/liter of FloraGro into my water for an aggressive vegetative growth period. This is basically all of the time, because of what I'm growing - herbs and lettuce that is constantly harvesting and never flowering.


In the guide and video I made, I bought soil starts that were a bit beyond seedlings to speed up the process, but I would recommend just starting with seed in the system so you avoid any dirt and bacteria that the soil might bring in. I get the brown jelly going on every now and then, and I think it's one of these:

• Water too hot
  
• Too much light entering reservoir
  
• Debris from the dirt transplant
  
  As for changing the nutrients, I do a recirculating system where I only replace the water that gets used by the plants. So I fill it up once to start and then add water as necessary. I keep a 5 gallon barrel of water that is perfectly pH'd with nutrients added to make it a LOT easier.
  
  To check the amount of nutrients you have going on you can spend 15 bucks and get this. It will let you know the parts per million of nutrient in your solution.
  
  
  As for pH, it really doesn't fluctuate very much. I check it every now and then but as long as you pH correctly at the start, add the proper amount of nutrients to the water and refill as necessary then you are balancing pretty damn well.
  
  
  I'm a bit confused on the science question, could you let me know what you mean by that?
  
  
  

El cheapo: http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

These cheap ones don't adjust to temperature, so you'll have to consider that if you're reporting your values for some kind of project. They calibrate it at 25 degrees C, so any temp lower than that is going to over-estimate your TDS.

pH is as simple as getting a test kit at a pet store.

I tested the distilled i was using and it read less than 5. Then my tap was 400, my shrimp tnak was 385 and my 20 gallon fish tank was at 550. So i think it was reading right. I ordered this one. http://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY?ie=UTF8&psc=1&redirect=true&ref_=oh_aui_detailpage_o00_s00
Im not sure there is a way to change it and i think it only measures PPM

Cheap TDS (total dissolved solids) testing kit:

https://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY

Or any meter that measures EC/TDS.

Water tester and filter system. Best items I bought that year.

https://www.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_3?ie=UTF8&qid=1504296326&sr=8-3&keywords=water+tester

https://www.amazon.com/APEC-5-Stage-Reverse-Drinking-Water/dp/B00I0ZGOZM/ref=pd_sim_60_2?_encoding=UTF8&psc=1&refRID=J4HVJXXMCEZP1BPW9F5D

You could've just gotten this, it's a digital water quality tester:
https://smile.amazon.com/HM-Digital-TDS-EZ-Measurement-Resolution/dp/B002C0A7ZY/ref=sr_1_8?ie=UTF8&qid=1493673452&sr=8-8&keywords=water+testing+kit