watering

[philwilliams]

I use tap water with a ph of about 8.5 for my cactus planted outside in the soil. From what I have read elsewhere in this forum cacti prefer water with a lower ph around 6. Is there anything I can put on the soil to acidify the water before it gets to the plants or will the soil do the job for me anyway? The soil is very sandy and I water twice a week when temperatures are in the 30's and 40's.

[iann]

You could put vinegar in the water. Putting something in the soil is not a practical way of handling it.

[insipidtoast]

I recommend you get one of those water pitchers with the cheap carbon filter. I've done pH tests of the water before and after when I was living in Reno, and 7.9 dropped to 6.2. I'm guessing this is due to the filtering out of calcium and magnesium.

[iann]

A carbon filter alone shouldn't change the pH because it doesn't remove dissolved solids.

A reverse osmosis filter, also commonly found in countertop pitcher devices, will reduce pH by removing most dissolved solids. A pH of 6.2 (assuming that is accurate) would be quite normal following reverse osmosis filtering. It would probably drop some more if you just shake it up to let more carbon dioxide dissolve. Probably won't quite handle the load for a greenhouse full of plants though

Distillation gives equally (or more!) pure water and relatively simple devices, home-made even, can produce large quantities of distilled water.

[hughjack]

try some nitric acid to adjust the water ph value

[RichR]

Phil, My tap water comes in at a pH of 9.8. I only have to add 1 TEAspoon of common white vinegar per 2 gallons of H2O to bring the pH down to 6.0. I buy vinegar at a wholesale club here for three dollars a gallon. This is enough vinegar to treat 768 gallons of water. I mix up 35 gallons of water at a time in a trash can (dust bin?) and water my outdoor cacti using a watering can. It takes a little longer than using a hose to water but I think it's worth it. I also put water in large tubs and in my rain barrel and let it sit for a week or so to let chlorine dissipate. Not sure if this is necessary but it can't hurt.

[cactusmerv]

Phil, I know this is 12 months since you posted your problem but I have just joined the forum and have been going through them all. Most waters, even if at a high pH, only have a very low buffering capacity ( ie it takes very little acid to produce a large drop in pH ). If your sandy soils in W.A. are like ours in Qld they will be quite acid , so adding alkaline water to the soil is, if anything, quite beneficial. Also, since soils have a high buffering capacity, it takes a lot of alkaline water of low buffering capacity to make any substantial change to the soil pH, and since most desert plants like a higher pH, you are probably helping your plants by watering with alkaline water. I would buy a cheap pH test kit from the local garden centre and if your soil has a pH of less than 7.5 then don't worry about treating your water. Even if your soil does turn out to have a high pH ( ie above 8 ), it is much easier to acidify your soil by sprinkling on some flowers of sulfur than to change the pH of your water every time you use it.
Cheers, Merv

[philwilliams]

Thanks for the info Cactusmerv, I've still yet to test the soil ph as i never got round to buying one of those soil ph test kits from bunnings, is there a way I can test the soil using the one I've already got for testing water ? - ie the one drop of liquid that you drop in a small vial type. And you're right about it being easier to change the soil ph rather than the water ph cause its a lot easier to stand there with a hose for half an hour than mix up hundreds litres of acid with water, Does flowers of sulphur last a while ?

[fanaticactus]

As long as there's a discussion of pH going, now might be a good time to ask this question. Where in the U.S. is a good place to get pH test strips for water? I went to a garden center and got a water test kit for $10 or so, but it only has two strips for overall pH and other strips for dissolved minerals. I thought that was rather expensive, especially if I need to keep testing samples after adding drops of vinegar to adjust the pH. Most swimming pool stores are now closed and hardware stores don't seem to carry them. Could I try a drugstore/pharmacy for a vial of maybe 50 strips or so for just a few bucks? Can I use the same strips used for testing urine, for example?

[SnowFella]

Pool shop would be a good idea for test kits I'd guess.

Wops, didn't read that fully. Ought to still be able to get pool test strips through ebay or your local big box store though.

[fanaticactus]

Pool shop would be a good idea for test kits I'd guess.

Wops, didn't read that fully. Ought to still be able to get pool test strips through ebay or your local big box store though.

OK, Snow. Thanks, that's a strong possibility.

[midlife crisis]

In regard to the question on ph test kits hydroponic stores will have what you are looking for. The basic kit that you add a drop to a water sample are cheap and last a long time. You just have to keep saying to your self I am not growing pot so it is ok for me to buy from here.

I am also with you all on the watering of out door plants. My Trich's are watered twice a week by my reticulation ( watering restrictions ) and during the summer heat I have to hand water as well. At the moment they are all in pots but once they go in the ground they should do ok with just the reticulation. With the number of hours that I already spend watering my garden during summer I just don't have the time to water with ph adjusted water. I do adjust the ph for my plants that are inside on my shelves but I have to water them with a watering can or bottom water any way.

Cheers
Midlife