Customer Reviews

Luster Leaf 1880 Rapitest Electronic 4-Way Analyzer

5 star:		(3)
4 star:		(5)
3 star:		(1)
2 star:		(3)
1 star:		(7)

 

 

I bought the rapitest mini 4 way soil analyzer on ebay which is almost identical to this one with three leads. I couldn't help notice how many are complaining that the pH measurements do not work. This is not true. If you follow the directions it measures pH fine.

You need to first clean the right lead with the included pad and wash it. Then you stick the meter all the way into the ground. Then you have to water the ground around the meter leads until it gets muddy almost like water. You will then see the meter start moving away from 7 and if you wait a minute, you'll get an accurate reading. Repeat a few times to make sure you got a good spot that is consistent. If you only insert the very tips of the leads into the soil or do not make the soil into mud, you will get a pH of 7. I've inserted the whole thing into a bottle of vinegar and it measures about 2.5 which is accurate and I've inserted it into a container of peat moss I've watered until muddy and it measures 4 to 5 depending on location. Both are accurate. If I do not follow the instructions and only insert the tip of the leads into the bottle of vinegar or stick it in dry soil or stick it into the soil without waiting a minute I get an inaccurate reading. But if you follow the directions it works fine with an error of about 0.5 pH units in my opinion.

I give it 4 stars out of 5 because the "Fertility Meter" does not appear to really measure N-P-K directly but seems to merely measure the soil's conductivity and assuming most of its ions are N-P-K compounds and therefore has a high false positive rate. When you insert it in liquids that do not have any nitrogen phosphorous or potassium, it reads "high" when it should really read "low". Also the pH meter appears to have a maximum error of 0.5 pH units with repeat measurements in vinegar which is fine for gardeners who don't work in a lab and need perfect results.

This unit is very useful for measuring soil moisture and sunlight. While I wasn't in a position to evaluate the fertility feature, I do know that the ph testing is useless.

When I tested the commercial soil in my potted plants, I noticed that they all indicated a ph of 7. To my surprise, my yard and garden soil also indicated 7. Since I have heavy clay soil in my yard I began to suspect that the Rapitest was inaccurate.

I took a couple 1/2 cup soil samples out of the garden and put them in small seed pots, carefully followed the Rapitest instructions for ph testing and still came up with a ph of 7. I added two tablespoons of vinegar to one of the samples and two tablespoons of baking soda to the other. Results? You guessed it--ph of 7.

I found a study on the Journal of Extension ([...]) that evaluated ph testing methods for field testing by extension agents which found the Rapitest to be useless.

I would have given this unit an even lower score, but at least two of the functions worked.

A very good device for the price. The only thing that I didn't realize at first was that the NPK numbers are not specifically given. Rather, the device gives you an overview of whether the nutrients are balanced or not. If the nutrients are not in the "ok" range, then you'll need to do a seperate nutrient test to find out exactly what the levels are.

The first meter I ordered from Amazon did not seem to function properly. The pH and moisture seemed OK, but fertilizer always seemed to read at the low-end of ideal and light always seemed to read 2000 fc no matter how bright or indirect the sunlight. I filled out a return online and had a replacement within 3 days and a free return label -- good service.

The replacement unit seems to function OK. Over the range of pH 6-8 the meter seemed accurate. I tested pH on distilled water (it was 7), on baking soda (it was 8) on soil of known slight acidity (it was 6-6.5). However, when tested on very acid soil (verified to be pH 4 with a chemical test kit), the meter read between pH 1-2.

The moisture meter seems to work fine. It read 0 on dry soil, 9 on soaking wet soil, and somewhere in between on moderately damp soil.

The light meter was way too sensistive. I compared it to a professional meter and it was reading 1000 footcandles when there was only 200 fc. I "recalibrated" it by putting black tape over 95% of the sensor on top until the readings matched the professional meter -- it is now more or less correct.

The fertility meter seems pretty accurate. I mixed up a batch of half strength Miracle-Gro fertilizer solution and poured it over some old spent soil and took a reading -- it read "Too little". Using regular strength MG it read "Ideal" and using double strength MG it read "Too much". I've used this weekly to monitor my fertilizer levels and tell me when to reapply my liquid fertilizer to different vegetables and this is the most useful (and difficult to find) function on a meter like this.

Something to note, you MUST insert the probes a full 3.5 inches into the soil for an accurate reading. This makes it difficult to use the meter in very hard clay soils or in shallow house plant pots (like my Bonsai trees).

- Rob Thompson

This thing is a piece of junk. The light tester just measures the amount of lumens and not the actual amount of good quality growing light. You Bring it right by a incandescent bulb (bad for growing) and is says 9 and outside it says 9, very worthless. The moisture test is either wet or dry, no in-between. And then the pH test doesn't work period. I tested it by putting it in known pH neutral water, 7, and it reads just over 6. Then I put it in OJ and then lemon juice and then vinegar. They all read the same, just over 6. I followed the instructions but the entire thing is worthless. Save your money and just buy the pH test strips or get a more expensive reliable electronic tester.

The one I have doesn't work at all, so I opened it up. The total price of all the components has to be less than $5, which makes $35 a rather outrageous purchase price. The components are the case, the probes, the meter, a 50 cent rheostat, a switch, a small photo cell, and a resistor. I can't see how that meager melange is supposed to produce meaningful results.

Isn't quite as easy to use as you are led to believe, but if you follow the instructions, you get reasonable results. It's not substitute for a good soil test, but I've found it to be a good indicator of when a soil test might need to be done.

Tests soil with a known ph of 6.0 as 7.0. That's a whale of a lot of difference. It does register that you are in direct sunlight when you are in direct sunlight - amazing, huh? I think that the soil fertility and soil moisture tests are correct. (Note that you can stick your finger in soil and determine if it is wet...) Spend your money sending your soil to a land grant university and don't buy this thing!

I made about 10 test with this analyzer from differnt areas and was not impressed at all with,everyone of the test tested about the same. One sample was as wet as thick soup and still tested dry. I also found it very hard to read the small numbers and wording. I sure would not waste my money on another one.

Right out of the box i tested light meter and nothing. Will the other functions work? Does it really matter now. Brand new and broken. Thank you China.