I new to this too and have the same problem. It's made more difficult by the fertilizer coloring the water.

I'm going to buy a digital pH meter.

This post was edited by boreal_wormer on Mon, Feb 17, 14 at 19:28

IâÂÂm thinking the same thing. I looked at some cheap ones on Amazon (PH-009 $7.83) but was told that eBay (Milwaukee $22.99) was more reliable. Then of course, there is the calibration solution to think about and then something about having to store it in a neural water solution. If you come up with anything please post, IâÂÂd like to hear what you find out. Mat

Hello all , I have tried several but I am now using a PH stick as per the photo easy to read with flashing points of scale in any light condition or nutrient colour , I am also using an EC stick as well very easy to read.
A little more expensive than some but worth every cent extra. on ebay in Australia about $38 .in the USA probably cheaper.

A meter is worth the money to start. Look at the margin of error for the model you want. Good ones are +/- .1 but some cheaper ones have a .2 margin of error. After enough time, you will get in the habit of doing things the right way so that you won't need the meter. But you might not know the right way in the first place without it.

You'll probably need two calibration solutions. Often they are ph 4 and 7. It's just colored water, and it stinks to have to pay so much money for it, but the meter is only as good as its calibration. It's best to not re-use the solution; pour out a tiny bit each time. You can use an old toothbrush with a dab of toothpaste to clean any salt buildup off your meter.

I have no need for the precision of a pH meter, so I just use the indicator solution, and the longer I'm doing this, my systems have become so predictable I know how my pH is going to behave for my plants (since I have a defined 100% change point to begin each 6 week cycle).

Being within 0.5 pH units is fine, though I don't have any trouble calling my pH to the nearest tenth. I'm sure it helps that I'm a chemist and have read pH for a long time, though it was probably the pool that deserves more credit ;-)

In any case, I would suggest you try what I do and see if it helps - get a bright white blank paper and fold it in quarters to get a solid white background. Place the manufacturer's calibration colors (if GH printed it on the bottle, then that) by or above/behind, and put it directly under a reasonably bright incandescent bulb, with a shade so the direct filament doesn't interfere with your eyes, until there are no shadows and the color is nice and bright throughout the sample. If you have some sort of plastic kit that is cheap or marked in a way that it is small or confusing, don't bother with it. I use some test tubes about 19mm diameter and angle them back to get a nice rich pure light. If I've been drinking or knocked on the head, or have been in low light reading for an extended period of time, I am more careful to compare the chart in tandem with the sample.

If you get test tubes, try to get shorter ones or it will be a pain to clean the bottoms.

To get good with indicator solution when you start dealing with it, make a few trials using tap and diluted vinegar just to get a few samples. The best is if you can do that and make a set of a few tubes at once at different pH. That makes you much more accurate since you directly can see the tones you particular solution makes, and they can appear different that the chart, but once you see what's going on, there will be little doubt. Also use a reproducible amount of nutrient solution in the sample, and a good eyedropper with say 3 drops each time. You'll get the hang of it, but really no one can do a perfect job with indicator if they try to do it outside with the lighting effects and background color interference for your brain to interpret. Good luck.

This post was edited by PupillaCharites on Wed, Mar 5, 14 at 1:37