Post by thread:measuring the ph, kh and co2 levels

Hi Goncalves, > I'd apreciate if someone could help me finding information about (or how > to do) kits/components to measure the ph, kh, and co2 levels of the > water. > Of course... if it is possible to do it! :) pH electrodes put out a millivolt level, so a bunch of amplifier is needed. can be implemented with pic. kH is this same as redox potential? very tricky to measure well, ive seen it done badly really often. Electrical conductivity--a snap. just measure 1/resistance across a 1-cm interval, can use gold-plated electrodes printed onto a piece of pc board EXACTLY 1 cm apart. CO2?? i dont know of an electrode method for water, only air. there is a sensor out for CO2 in air. i use wet chemistry for CO2. Forestry Suppliers has a CO2 test kit by LaMotte Scientific, 22$ cheap. What are you measuring? a dump? alice

At 12:08 AM 5/05/99 -0800, you wrote: > Hi Goncalves, > >> I'd apreciate if someone could help me finding information about (or how >> to do) kits/components to measure the ph, kh, and co2 levels of the >> water. >> Of course... if it is possible to do it! :) > >pH electrodes put out a millivolt level, so a bunch of amplifier >is needed. can be implemented with pic. This is relatively simple to do. >kH is this same as redox potential? very tricky to measure well, ive >seen it done badly really often. If REDOX, just use a REDOX electrode which are readily available. It gives a millivolt output. >Electrical conductivity--a snap. just measure 1/resistance across a >1-cm interval, can use gold-plated electrodes printed onto a piece of >pc board EXACTLY 1 cm apart. Having been through electrical conductivity measurements and countless re-designs I can say it is NOT simply a matter of doing what is suggested. You may be lucky but it will depend on your range, resolution size of container and other factors. Peter >CO2?? i dont know of an electrode method for water, only air. there >is a sensor out for CO2 in air. i use wet chemistry for CO2. >Forestry Suppliers has a CO2 test kit by LaMotte Scientific, 22$ >cheap. > >What are you measuring? a dump? > >alice >

Hello peter, Of course you are right, if what is needed is a lab-quality instrument, not something for messing around with. I was thinking of the little $99 EC meter in my desk drawer here, which when i look into the cup i see a circuit board with two gold-plated electrodes 1 cm apart. yes, when you need it, then the carbon resistors and temperature compensation and so forth are needed. ive used a voltmeter and a cork before...i used it to show a client that the seepage out of his slope was seawater, not freshwater from the irrigation system, and he'd need big dike to fix the problem. regards, alice > > Having been through electrical conductivity measurements and countless > re-designs I can say it is NOT simply a matter of doing what is suggested. > You may be lucky but it will depend on your range, resolution size of > container and other factors. >

AHHH!!! That's Great! Saltwater Aquarium right? I've recently designed my own pH controller. I haven't had the time to build it yet though. I'm also working ( in my very limited spare time ) on a PIC based aquarium controller. The intent is to control : pH, ORP, water level, and temperature. It will also need a real time clock for turning the lights on and off. pH is measured with an Ion Selective Electrode (a pH probe). It has an output of -59mV for each pH unit above nuetral and +59mV for each pH unit below nuetral. i.e. a pH of 9 would be -118mV and a pH of 5 would be +118mV. The input impedence of the probe can be as high as 10e+9 ohms. I'm planning on using an AD 620 Instrumentation Amplifier as the input amp. dKH (or just KH) is the designation for German Degrees of Hardness, or degrees of Carbonate Hardness, which is a measurement of Carbonate Hardness. In most natural waters, Calcium and Magnesium make up more than 99% of this hardness. 1KH = 17.86 mg/L of carbonate hardness as CaCO3. I am not aware of an electro-chemical means of testing this parameter. A colorimeter would be your best bet if you'd like to automate this test. I would be very interested in working with anybody who has a few ideas on building a colorimeter! This one has been eating at me for some time. One of these days I'll have to quit my job so I have the time to figure out how it's done. I believe there are probes for measuring CO2 concentration in aqueous solutions. I'd have to take a look in a few catalogs. I can point you to a few good OEMs if you like. Hach Chemical sells VERY high quality stuff. All professional laboratory grade stuff. http://www.HACH.com Orion also sells a great deal of ISE stuff. http://www.orionres.com And finally Omega Engineering. They have just about everything. If you can get them to send you their 5 or 6 free catalogs (about 25 lbs. worth), they have excellent tutorials in them on pH measurement and much more. http://www.omega.com I'd be happy to share my schematics and PCB layouts for the pH controller with you if you like. Send me a private email and I'll send them off to you. Erik Goncalves wrote: {Quote hidden}> > Hi, > > I'd apreciate if someone could help me finding information about (or how > to do) kits/components to measure the ph, kh, and co2 levels of the > water. > Of course... if it is possible to do it! :) > > TIA, > > Goncalves > cg2KILLspamarauto.uminho.pt