[dbrody]

I need a water soluable inert solid material.  It is to be mixed with a water soluable pH Buffer in order to dilute the concentration of the final material.  Any recommendations?

Thanks.

Dave Brody

[Borek]

Sand?

[dbrody]

It needs to be water soluble and inert.  Is there sand that is water soluble?

[Borek]

Sorry, inert solid usually doesn't mean soluble - my mistake. But then kitchen salt will be close, or if you want it to be not ionic glucose or sucrose. But I am afraid it will not work the way you expect - if you dissolve a lot it will be no longer water solution, so pH will be not what you want it to be. There is no easy solution to the problem as presented.

[dbrody]

We are taking a pH buffer solid compound and trying to dilute it so we can include a standard "measuring cup" in the package (i.e. a 1/4 cup).  The current compound is too concentrated.  The pH buffer compound is used to adjust water for plants, so whatever we use cannot affect the plant.  I'm sure there is something that doesn't affect pH, is a solid, water soluble, and doesn't affect plant life.

[Borek]

I'm sure there is something that doesn't affect pH, is a solid, water soluble, and doesn't affect plant life.

I am not sure such thing exists. Everything that is soluble will change osmotic pressure of the solution, changing its properties in a way that can be not tolerated by plants. Effects of hight tonicity can be classified as physiological drought.

Why do you want it to be soluble? Sand will do the trick of diluting the solid, than it will just find its way to the bottom of the tank.

Seems to me like it may be easier to just look for some another measuring cup.

[AWK]

What about polyethyleneglycol?

[doc30]

Is there a reason why you cannot dilute this aqueous buffer with water? Why are you using it on plants? If the buffer concentration is not safe for the plants, perhaps a different buffer is needed.

[dbrody]

Unfortunately the end substance needs to be dry.

I looked up the effects of polyethyleneglycol on plants and found the following.  It is used to simulate drought conditions in plants, so probably not good to use it for this application -

"Even PEG of high molecular weight, such as 4000 to 8000 was found to be taken up by plants. PEG was found in shoots and roots. PEG was taken up by maize and bean plants at a relatively slowly rate of 1 mg/g fresh weight per week. However, when roots were damaged or broken, rate was higher. Cotton absorbed less PEG (Lawlor, 1970). Pepper plants also took up PEG, where the higher molecular weight PEG was mostly concentrated in roots while the lower molecular weight compounds accumulated in leaves (Janes, 1974). Yaniv and Werker (1983) presented striking photographs of PEG 1500 to 6000 mw deposited on leaves of various solanaceous plants exposed to PEG in the root medium for 24 h or less. Again, greater deposition was seen in plants with physically damaged roots. PEG 6000 was taken up by tomato plants and found in older leaves and roots (Jacomini et al, 1988).  The critical finding was that leaves containing PEG behaved hydraulically differently from leaves without PEG when grown in PEG containing nutrient culture. It can therefore be concluded that PEG, even of higher molecular weight, is taken up by plants and the rate of uptake and concentration in shoots and roots depends on the species, on PEG concentration, on time of exposure and on root damage."

[Lv2sfo]

polyvinylalcohol

water soluble and very safe, I don't have any flora specific references for you but it safe in the body