Conductivity Sensor

[Ian Stirling]

Luhan Monat <x@y.z> wrote:

Ted Edwards wrote:
Luhan Monat wrote:

The picture is a week out of date. I've gone to nylon ties with a
piece of mousepad between the jars and the PVC. We are running over
100 here every day lately - the rubber bands were almost totally
decomposed in about 2 weeks.


Use stainless steel hose clamps - cheap and readily available from
automotive suppliers. Nylon ties die fairly quickly if exposed to UV.
So do most tapes.

If the nylon dies, I'll definitely go to the steel hose clamps.

Black nylon is pretty much immune to UV, at least in the near term.

 

[Dan Major]

Luhan Monat <x@y.z> wrote in news:No7we.3594$Qo.2539@fed1read01:

Yo,

Measuring conductivity is standard procedure for hydroponics. My tests
so far, show only about a 10% change in conductivity between water and a
specified nutrient solution. From further study of Hydro systems, I
may just start with a standard mixture and have the system add plain
water to maintain the concentration.

Once I get some plants in, I'll post some more pictures.

Yo, backatcha

There are other ways than conductivity to measure what's in a solution,
although this is an easy method. You want to know the levels of specific
nutrients. There are ion-specific electrodes available, that work much the
way pH electrodes do. Additionally, I;ve seen devicesthat use an ion-
specific photochemical sensor, a fiber optic cable, and a photosensor for
concentration measurement. Depending upon how much money and how
complicated you want to get, there are more than one way to approach the
solution (pun intended).

 

[Luhan Monat]

Dan Major wrote:

Luhan Monat <x@y.z> wrote in news:No7we.3594$Qo.2539@fed1read01:


Yo,

Measuring conductivity is standard procedure for hydroponics. My tests
so far, show only about a 10% change in conductivity between water and a
specified nutrient solution. From further study of Hydro systems, I
may just start with a standard mixture and have the system add plain
water to maintain the concentration.

Once I get some plants in, I'll post some more pictures.


Yo, backatcha

There are other ways than conductivity to measure what's in a solution,
although this is an easy method. You want to know the levels of specific
nutrients. There are ion-specific electrodes available, that work much the
way pH electrodes do. Additionally, I;ve seen devicesthat use an ion-
specific photochemical sensor, a fiber optic cable, and a photosensor for
concentration measurement. Depending upon how much money and how
complicated you want to get, there are more than one way to approach the
solution (pun intended).

Hmmm,

Maybe several years down the line, I may get into such technicalities.
As for the initial setup, I have decided to only monitor the water level
in the reservoir (with a pair of electrodes). One source indicates that
just keeping the water level up is sufficient for a couple weeks at a
time; then the entire system is dumped and changed out with a measured
nutrient solution.

--
Luhan Monat: luhanis(at)yahoo(dot)com
http://members.cox.net/berniekm
"Any sufficiently advanced magick is
indistinguishable from technology."

 

On Sat, 25 Jun 2005 12:39:29 -0700, Luhan Monat <x@y.z> wrote:

Hi,

I'm constructing a Hydroponics system, and need to monitor the
conductivity of the nutrient solution.

Any suggestions on what to use for the sensors for stable long-term
readings?

Thanks,

Use stainless steel up to about 2000 uS and porous graphite up
to 10,000 uS.

I'm fond of non-contacting conductivity, but building a
home-brewed system would be quite a challenge.