I'm wondering why conductivity, specifically. Is it really a good indication - well, I know it would be a good indication of concentration of _every_ kind of ion, but wouldn't distinguish between nutrient A and nutrient B; or then again, are you using a premix and just need to know when to add a teaspoon of mix or whatever?
But for plain ordinary conductivity, I was going to say platinum, but that two-toroid idea sounds pretty intriguing.
Good Luck! Rich
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.
-- Luhan Monat: luhanis(at)yahoo(dot)com http://members.cox.net/berniekm "Any sufficiently advanced magick is indistinguishable from technology."
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."
Black nylon is pretty much immune to UV, at least in the near term.
Luhan Monat wrote in news:No7we.3594$Qo.2539@fed1read01:
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).
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.
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