I've liked the pH 4-7 strips from sanitationtools.com. They have other pH range strips. But I've used these to adjust well water to pH in the 4-4.5 range using battery acid.

Here is a link that might be useful: sanitation tools pH strips

If you are able to get a reasonably clear signal from the pH paper you are using, then I would stick with that method. I am currently using dye indicator solution to check soil pH around our blueberry shrubs. Bromocresol green indicator will turn the sample yellow if the pH is 3.8, blue at pH = 5.4, and varying shades of green if the pH is between these two values. One source for indicator dye solutions is HMS Beagle.

After growing very frustrated with the Lamotte test strips that I bought late last year, I bought a General Hydroponics pH test kit a few weeks ago and really like it. For whatever reason, the test strips didn't provide an accurate reading for a water/vinegar solution -- the color stayed virtually the same for 1 tbsp of vinegar per gallon up to 1/2 cup per gallon.

Thanks to all for the quick response.

@fruitnut: for tap water 4-7 range is good or I can go for littler more wider range 2-9 for the pH test strips available in sanitationtools website?

@shazaam: I couldn't find an option to buy the pH test kit from General Hydroponics website. Are they sold at HD, Lowes are any other retail stores.

Also, please let me know how does it work and what pH ranges it can display the pH restults.

The GH kit is available from a variety of online retailers, but I doubt that you'll find it at any local retailers (unless you have a neighborhood hydroponics store). I bought mine on eBay for $7 or $8. In order to test water, you fill the enclosed vial half full, add 3-5 drops of the solution, and then observe the color. It provides readings from 4 to 8.5.

Shazzam,

The reason you could have trouble with the strips is you water could be very hard like mine. When I add 93% sulfuric to my water if I add 1/4 cup to 300 gallons or 1/2 cup the PH does not change at all. While that seems counter intuitive it actually makes perfect sense. The acid is reacting with the bicarbonates but until most of the bicarbonates are dealt with the PH remains high but once you hit the tipping point the PH drops fast with just the addition of a small amount of acid.

For testing I prefer to use two types just because it makes me feel better when they agree. I use rolled paper and strips. For the soil can't go wrong with the kelway.

That was my first thought -- that my water was very hard, and that it was going to take a LOT of vinegar to get it to the right pH. At that point, I began considering a stronger acid. In the meantime, I decided to go with a 1/4 cup of vinegar per gallon in the hope that this would be good enough. Soon thereafter, I began noticing chlorotic leaves on some rabbiteyes, and then it expanded to several highbush cultivars, as well. For a few reasons, this didn't make sense as high pH induced, and I began to wonder if I had the opposite problem. So I bought the General Hydroponics kit, tested my irrigation water (with fertilizer and 1/4 cup of vinegar per gallon), and discovered that the pH was below 4. I dialed back the vinegar until the color was in the 5.5 range, which turned out to be a ratio of approximately 1/2 to 3/4 tbsp of vinegar per gallon of water. I've been watering at that rate for several weeks now, and the formerly chlorotic leaves are greening up nicely. There might be another factor at play, but, at this point, I'm trusting the General Hydroponics reading.

Vinegar will work OK at lowering soil pH, but the effect is temporary, lasting a few weeks or maybe a month at the most. If you water the shrubs often, and add vinegar every time, this method will work, but that is time consuming and gets to be expensive. It is thought that bacteria living in the soil actually consume the vinegar, and so it disappears. When sulfuric acid is used to lower soil pH, the effect can last a year or more. But you have to use caution, and dilute the acid correctly.

That's a good point about vinegar, eric. You're absolutely correct -- since they're metabolized by soil microorganisms, organic acids have only a temporary effect on soil acidity. If you're growing in ground, this is something that you really need to understand, and I think the argument for a non-organic acidifier like sulfuric acid makes a lot of sense in this context. Since all but one of my blueberries are in containers, though, this is less of a concern for me. To borrow words from tapla, a frequent post in the Container forum, "vinegar and citric acids are indeed poor as remedies for mineral soils...but they are both very effective and inexpensive ways to temporarily lower the pH of the soil solution in container culture, 'temporary' being all the container grower needs."

It also is important to get fresh or properly stored pH strips. For a while I was trying to use some 1 yr old ones, and getting odd results. I tested one in straight vinegar, and got no change in the color. Threw those strips away and got some fresh ones and now can see expected results.

Around here, my local HW store (not the big box one) carries pH strips in rolls, for various ranges.