List of water tests to be done?

[jonnyq]

Greetings,

So there have been several threads on CP water quality, so I just thought that this might be the time to throw my hat in...

Is there a list of tests that should be run on water to determine its suitability? Dissolved solid ppm using a digital water meter is, as I understand it, a good start (although i'm not entirely clear as to what solids they are testing for...?), but are there more specific tests to run in ADDITION to these? Sodium, calcium, aluminum? Are there specific tests for these, or is this what the water meter tests for...



As I understand it, from best to worst for CPs:

Distilled water -> rain water -> RO water -> all else at own risk

...with the "all else" including your local documented tap water, and even water from household dehumidifiers, which seems to have both strong proponents and strong opponents...

(Right now I'm using distilled, and collecting rainwater in a motley array of plastic containers... but I'm concerned that the myriad of dirt/debris that blows INTO the collecting containers is introducing more dissolvable solids into the rainwater...)

[jdallas]

Hi Jonnyq,

I noticed your thread on this subject, and I'm assuming you watched my segment on water in the DVD. I don't think I got into the chemistry too much in the video, but the minerals that are the problem for cp are calcium and magnesium. They tend to change the pH of the soil and plants absorb them. Other things can be of concern, but these are the two biggest offenders.

For many years I used well water on my plants from my fathers property in our are with no ill effects. His well had a ppm of about 140. However, his dissolve water solids were mostly iron which didn't seem to affect the plants nearly as much as calcium and magnesium.

Sodium can be a problem also, but this is usually just from home water softeners.

The small amount of debris getting into your rainwater is probably of little concern.

There is a new small filter on the market now that does take out all dissolved solids if you're looking for some small scale filtration. It's called "Zero Water", and it even comes with a dissolved solids meter. It uses an ion exchange filter. If you buy the bigger filter packs it ends up costing about the same as using the grocery store machines that dispense R.O. water.

Jeff

[jonnyq]

Hi Mr. Dallas!

Jun 15, 2010 15:34:15 GMT jdallas said:

I noticed your thread on this subject, and I'm assuming you watched my segment on water in the DVD. I don't think I got into the chemistry too much in the video, but the minerals that are the problem for cp are calcium and magnesium. They tend to change the pH of the soil and plants absorb them.

Ahhh... I see... Hence your demonstration of the pool pH strips. So it's not that the pool strips and the meter need to be used in succession to test for different aspects of water quality, but rather that each is an alternative method for essentially testing the same thing?

However, his dissolve water solids were mostly iron which didn't seem to affect the plants nearly as much as calcium and magnesium.

Ahh... So as long as ppm<50 I shouldn't have to worry about ancillary tests to determine what ions those parts per million actually are, per se...

(btw, my mention of aluminum stemmed from a discussion I found on another forum regarding the use of dehumidifier water. There was some concern that aluminum tubing through which the water passes may be introducing aluminum into the water. There was then discussion as to whether or not aluminum was actually detrimental to cp health... In either case, I'll likely stick to collected rainwater for now. )

The small amount of debris getting into your rainwater is probably of little concern.

That's outstanding to hear... *whew*

There is a new small filter on the market now that does take out all dissolved solids if you're looking for some small scale filtration. It's called "Zero Water", and it even comes with a dissolved solids meter. It uses an ion exchange filter. If you buy the bigger filter packs it ends up costing about the same as using the grocery store machines that dispense R.O. water.

I shall indeed look into that, thanks again!

[runnervalentine]

i think that the test for dissolved solids and PH are for separate things and should both be done if your worried. I dont think that you can substitute one test for the other. Distilled water should registar as zero on a dissolved solids test, however it has a PH of 7 which is not the best for CPs, they like more acidic water so a PH of 5. rain water is aprox 5-6 maybe diff depending on where you live and that it why CPs like rain water so much.

So i would not use only one test. Both should be used in conjunction. If you use Distilled water, add a little white vinegar to a gallon (maybe a table spoon) and test the PH until is near 5.

[Not a Number]

Using distilled water with a neutral pH should not be a problem if Sphagnum (peat moss, long fibre sphagnum or live moss) is used as part of the substrate. Sphagnum will supply the acidity.

Whenever I've used vinegar to modify the acidity I've ended up with huge fungal blooms such as the white mass pictured in another thread.

[jonnyq]

Thanks for the suggestions, all!

My water meter arrived today with the ZeroWater filter... It looks like my tap water is ~41 ppm and the rainwater I've collected (in spite of the debris) is ~8 ppm, which is indeed of little concern. My "rainwater debris" paranoia has been assuaged, and it looks like I suddenly have more plausible watering options than previously, so thanks again!