A tap water problem, possible scenario?

[ballplayer 2]

My tapwater is very hard. I adjust pH, and let pH tested water sit in the vial overnight. I use the pH color dropper kit to get a ballpark figure. Invariably the water left in the test vial overnight jumps from the adjusted level (6.0-6.5; for soil/soilless) to at least 7.5-8.0 within 24 hours. If left for a few days the water is the color for the highest reading on the dropper kit (like teal/blue).

I typically use a ratio of 10-20% tapwater and 80-90% RO water. So my question is: is it likely that medium is enduring the same pH upswing 12-24 hours after irrigation? Especially when combined with some (even a marginal amount of) lime in my soil mix?

Just wanted some info from people more knowledgeable than me about how soil/peat based mediums react to water similar to mine. I am considering going all RO, but am unsure how to handle plain water irrigations. ie.. water with straight RO water in between fertigations. Is it advisable to water with a very light fertilizer mix with base nutes and Cal-Mag? or better to water with 0-20 ppm RO? All input and experience on these matters is greatly appreciated. Thank you for your help.

BP2

 

[Greenwork]

Hey BP2,

its not hard to give you a complete answer to your questions. water - this is on of the masterpieces of grwoing with plants. especially for a non native english speaker like me

But you should definitely keep in mind, that RO water, or water with very low ec (like your mentioned 200ppm) does not have much (any) acid-holding-capacity (sorry dont know the english word for it; couldnt find it in dictionary).

in genreal i would not advise to "play" with lime in the soil unless you are a very experienced grower with mixing soils AND knownledge about water.
the topic water is a very big AND important one, but u should find plenty of information about that in the net - especially on "normal grower" sites. i would advise you to look into the fish/aquarium forums as well; those guys are really pro´s concerning the water topic!

i would first advise you to buy a decent ph- and ec-meter. -you can throw away those drop test kits imho.
then you could mix yout tap water with Ro to a level of about 300ppm for soils, or 400ppm for soilless mediums or coco coir as well.

 

[Greenwork]

...sorry, of course i meant: it is not easy to give you a "complete" answer...^^

 

[TheCleanGame]

---snip---

 

[Greenwork]

Me guess a hint like "a cheap pinch of mag" is quite hard to follow for someone who doesnt know too well about water and nutes.
but he could give it a try.

 

[TheCleanGame]

---snip---

 

[ballplayer 2]

Thank you for the replies guys. Greenwork I do have some knowledge of water properties, pH, and nutrients. I think I am going to stick with RO water. Just unsure how I will handle "plain" waterings. I will most likely give plain, un-pH'd RO water, and allow the medium to control the pH in those situations.

My tapwater pH seems nearly impervious to long term pH adjustment. My main concern is if my saturated medium is enduring the same climbing pH as the test vial full of water is. I could easily see that rising, extremely high pH causing problems post-irrigation. I will also use a small amount of epsom salt to provide Magnesium and sulfur. Thank you for your interest.

BP2