PH test kit

[Herts Mike]

Does anybody know of a reliable kit to test the water I put on the plants? Soil test kits don't work I am told.

[iann]

You don't need a soil test kit to test water. Universal indicator, test strips, or the soil kits themselves will all do the job. It is testing the pH of things that aren't water that is tricky.

Of course you can guess what the pH of your water is going to be (between 7 and 8, possibly even a little higher if it is very hard), but the hardness may be more important. You can get a simple measure of this (the carbonate hardness at least) by titrating your water with a known acid. Soft water that has been made slightly alkaline using something sodium carbonate or sodium hydroxide will very easy become acidic, while very hard water will require a lot of acid before it becomes acidic.

[Herts Mike]

Indeed Iann. I want to be sure I am adding the correct amount of acid rather than hit and hope.

[iann]

Indeed Iann. I want to be sure I am adding the correct amount of acid rather than hit and hope.

Always fun to test your rainwater too, which is of course what you should be using

[Herts Mike]

We have a drought in Hertfordshire!

[DaveW]

I use simple cheap PH test strips off EBAY.

http://www.ebay.co.uk/sch/i.html?_from= ... s&_sacat=0

[D^L]

Our tap water has a pH of 8 to 8.5. In my experience rain is about 5.5. However the measurement accuracy is no better than +/-0.5.
I use vinegar to acidify the water but, as was discussed above, about 70% of the vinegar goes into getting rid of the carbonate buffer so I think the idea of testing is a good one.
My experience also is that the reactions are not that fast and you need to wait until the pH is stable before using the reading. I seem to remember that that took and hour or two, but I did the calibration a long time ago now. Perhaps that is just how long I waited to be safe.
Cheers
David Lambie
Bristol

[iann]

We have a drought in Hertfordshire!

Pretty dry here too but I still have water. Just enough showers to keep me topped up, like the hailstorms today.

[Herts Mike]

Thanks for your advice guys.

[gerald]

Not everyone will want to spend the money, but I've wasted so much £££ on useless 'kits' and cheap Chinese litmus paper with vague colours (exactly which shade of yellowy green is that?) over the years that I got one of these a couple of years ago and I've not looked back:

http://www.ebay.co.uk/itm/Essentials-pH ... SwMVdYFlHa

It's accurate to 0.1 of a pH value which is very useful when you bear in mind the logarithmic scale of pH where pH 6 is actually 10x as acidic as pH 7.

I also grow giant pumpkins which require specific nutrient solution, not just cactus, so it has added benefit to justify the cost.