Are the liquid type Ph test kits accurate?

Liquid Ph test kits offer the grower an inexpensive alternative to the expensive test meters and give results which are accurate enough to accomplish the task just fine. Usually reading within +/- two tenths of a point (.02) of electronic meters, depending on the kit.

For the grower looking for the most accurate Ph control, there are many various electronic Ph testers available that when calibrated will give extremely accurate readings. Unfortunately for quality units, you may be looking at a higher price than you are able to pay, even the best units will suffer down time as probes go bad. Ph probes are especially prone to failure as the membrane ages, eventually drying out and failing.

The most common solution to fill the void is liquid type Ph test kit.
They're quick, reasonably accurate and very inexpensive.
Great backup in case your probe fails.

When using liquid Ph testers, there are some important things to keep in mind:

Always use a white background when looking at the color in the vial.

A non white back ground can alter the color subtly enough that you may end up being off by anywhere from a little to a lot depending on the color background being used.

Make sure that all color comparisons are done under natural light or normal household lighting and NOT HID light, as the red/blue spectrums of the light (HPS and MH respectively) will cause serious variations to the appearance of the solution, and in some cases you could be running your solution as much as a whole point above or below what it should be.

It is always better to go for a ph strip or ph testing kit that offers accurate and reliable results. Some ph strips cannot be seen properly and some are not accurate. The colors correspond to a scale from 0 to 14--the lower end of the scale indicating acidity, the higher end alkalinity, and 7 representing pH neutral.

There is a cheaper option available, that I use and have checked it against pool water testing kit that I purchase for $ 7.00 USD at wally world. it's a combination light, moisture, and Ph test meter! I like the moisture meter on it, as it has proved it's self to me. Clearly it's not the best but for 7 dollars it's better than nothing! for those of us learning on a budget!

I've seen them at Home Depot and a few of the local gardening stores, all were about the same price as you mentioned. I have read on multiple forums that those are pretty good for moisture meters but their pH accuracy is often questionable. Due to this I would hesitate to recommend them but if yours is giving good readings that's great

However, I would be sure to check it against distilled water (~7.0, give or take a tenth) each time you use it and also on occasion double-check your readings against a liquid test kit (or a digital meter if you have access to one)...just to be sure it doesn't begin to give strange readings and consequently causing you to wrongly adjust your watering solution's pH. Even digital meters need calibrating once in a while and the calibration should be checked prior to each use.

Yes you are correct! That's why I stated that I checked it against, pool test strips, I might not have been clear about that? I don't check the accuracy before each use, and only suggested it as cheap option for those growing poorman, it's better than guessing!

Haha, no...you were quite clear I was just saying that it would be a good idea to check it prior to each use. I do that with the $20 Milwaukee digital meter I have just to be sure it's reading accurately. Doesn't hurt and only takes a few seconds for added peace of mind. That and calibration across the spectrum could become an issue at some point I'm sure hence checking it against a liquid tester every once in a while, the liquid won't tell you exactly what it is but will let you know if your meter is starting to get way off (0.5 or more).

Calibration is not something that is ever guaranteed to stay correct. Even radar guns and lab-grade equipment has to be calibrated from time to time. You don't want erroneous readings causing you to alter something for no reason.

what about the bluelab trunchoen?

I have a question - when using molasses water which is already brown - gold from coloring, does ph testing with liquid tests still yield accurate results ? or is it made inaccurate by water color ?

Growheart said:

I have a question - when using molasses water which is already brown - gold from coloring, does ph testing with liquid tests still yield accurate results ? or is it made inaccurate by water color ?

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Good question! I was wondering the same thing but with fish fert.?

gorillagrow said:

There is a cheaper option available, that I use and have checked it against pool water testing kit that I purchase for $ 7.00 USD at wally world. it's a combination light, moisture, and Ph test meter! I like the moisture meter on it, as it has proved it's self to me. Clearly it's not the best but for 7 dollars it's better than nothing! for those of us learning on a budget!

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I've used those but I believe mine was just a soil pH tester with moisture too. But hey they can work I see why not accuracy is not best though as stated. In order to receive more accurate info (I suppose those deals are metal with an end where it picks up what it is) take scotch bright and thoroughly clean the testing end with it making sure not to contaminate it with your fingers and other stuff afterwords. I don't know if you know that or not, but saying that couldn't hurt.


With the molasses and fish ferts it's all trial and error, keep on doing it until you believe you figured it out (watch when you start dropping it in an as it changes color).


My Hanna digital pH tester in my opinion was crap, I'm looking into other high end models for accurate readings good pH is key to an awesome grow.


And good info MM! Put it well, the sky can be useful too depending on day, you can work with different angles outside etc.

I have used many ph test systems and didn't like using the manual kits, but i do use them when digital fails, the economy ph pens from my exp shouldn't be used. they tend to fail right when I need it to work and retailers here suck replacement was so frustrating that I set up my own account with Oakton/Millwakee they are very helpful and the ph pen that i use has been working good for over 1yr it cost more for me but its worth it to me not to have to go to an infested unreliable vendor to be sold whatever budget p.o.s. they have in stock. Competition has helped alot local retailers are better now, but they are infested and have about as much advice as auto parts stores do with there products, they aren't growers with expert advice, and the auto parts seller isn't a mechanic. They do have some experts, mostly just sales people.

Just need to share my ph pen died on chlorine o.d. from municipal water supply I was buffing with peroxide didn't mix and tainted membrane, so had to use the old standby of fluid type or what I call the Jethro method to finish. dried out probe and cleaned it 4.0 cal solution it's working but will replace it and get spare electrode/membrane. expensive tools aren't needed but they do help

I should also add that the meter or p.h. pen that I like best is the Milwaukee ph51, it a single point calibration model, it's got screws next to batteries for calibrating, it's very user friendly and has been durable. The digital calibration type's are junk in my opinion and combo units are questionable as well.

My bluelab combo meter cost me alot but has been well worth it. Without it I never would have known how much I was messing up, my ladies are looking so much better this go round. But with that said, one problem solved only gives me pause to see a different one I never would have noticed. Happy Growing to all!

Lil Neutrino said:

However, I would be sure to check it against distilled water (~7.0, give or take a tenth) each time you use it...

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Do not do this; use the test solution instead. Distilled H2O is neutral, theoretically. Practically, it is very difficult to get distilled water with neutral pH in regular equipment setups. Carbon dioxide in the air becomes reintroduced during the condensation forming carbonic acid and will reach a dynamic equilibrium with that (CO2) of the atmosphere. The carbonic acid increases acidity of distilled water and lowers the pH level to the 5.5 - 6.0 range, generally.

The test strips are quite effective and reliable but to get in the 0.2 probable error range you must specify the 'narrow range pH strips'.

I see that I'm replying to old posts but I couldn't let it pass.

My first post - I suppose I should have introduced myself first.

Listen bro you have got to use a digital ph tester period if you are going to do any serious gardening. It doesnt have to be an expensive one but a Milwaukee Ph-600 is a good one and it retails for $29.99

Couldn't have said it better myself! good words man!!!

I used the cheap drip ph testing for 2 weeks, then just got a pen. Much better