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Re: DIY TDS Meter

Posted: Sun Apr 24, 2011 12:24 am
by Jimmy
i think i have some resisters somewhere, i will look for them. We had a three day weekend, but i try on Monday.

Re: DIY TDS Meter

Posted: Mon Apr 25, 2011 8:43 pm
by Jimmy
I had a nice chat with my chemistry teacher today. He did not seem to think that conductivity would give an accurate ppm reading because we don't know exactly what is in the water. It could be different ions, and salts, and minerals, we just don't know. All the different things would have different amounts of resistance, and some would not be conductive at all, these would go unaccounted for. He recommended boiling down the water and measure how much stuff is left over.

Re: DIY TDS Meter

Posted: Mon May 02, 2011 12:24 am
by 95slvrZ28
If we were looking for total ppm boiling would really be the only way to get a true answer, but remember that a digital TDS meter measures conductivity. We aren't looking for things that can't be dissolved in the water though. You can have as much SiO2 (silica) floating in the water as you want and it's not going to make any difference to the plant because it's inert. We're mostly concerned about things that are ionically bonded and easily dissociated by water, namely salts. Since the ions are easily dissociated by water they're going to make the water more conductive, although the different salts are going to have different conductivities (refer to the table here http://www.appslabs.com.au/salinity.htm ). Since they have different conductivities we've kinda been running with a worst case (NaCl is a factor of 0.51, we've been using 0.70).

Re: DIY TDS Meter

Posted: Wed Aug 12, 2015 7:29 am
by Creeper0629
Hi y'all,I'm not sure if this thread is still active,but it is a subject I'm dealing with.as I primarily deal with hydroponics to grow anything,this would be a massive aid in my fine tuning of nutriant solution. I have a mm,no tds meter,don't think iv ever even seen one.I mostly mix nutes on instinct and experience. I'm wanting to advance my skills however so I'm trying to find how to measure tds with my mm.I'm OK in math,and handle ohms law well as I have feild experience as an electrician, but this formula is new and may have to be broken down beter for me.tds calculated app would be slick here,like the ohms law calculator apps.any way I can use some help here and thanks in advance

Re: DIY TDS Meter

Posted: Wed Aug 12, 2015 3:21 pm
by Anymal911
^^^le wilde necrobump appeared

Re: DIY TDS Meter

Posted: Wed Aug 12, 2015 4:55 pm
by katya_dog1
Anymal911 wrote:^^^le wilde necrobump appeared
Does it matter? :)

Re: DIY TDS Meter

Posted: Wed Aug 12, 2015 4:58 pm
by katya_dog1
Creeper0629 wrote:Hi y'all,I'm not sure if this thread is still active,but it is a subject I'm dealing with.as I primarily deal with hydroponics to grow anything,this would be a massive aid in my fine tuning of nutriant solution. I have a mm,no tds meter,don't think iv ever even seen one.I mostly mix nutes on instinct and experience. I'm wanting to advance my skills however so I'm trying to find how to measure tds with my mm.I'm OK in math,and handle ohms law well as I have feild experience as an electrician, but this formula is new and may have to be broken down beter for me.tds calculated app would be slick here,like the ohms law calculator apps.any way I can use some help here and thanks in advance
Buddy, you'd be better off just spending $10 on a TDS meter. This is a cool idea, and it is certainly useful, but you'll go through a lot less stress if you just spend that ten bucks, especially for hydro nutrients. I formulate my own by weight, so I don't monitor PPM, but if I felt the need I'd just use my TDS meter.

My $0.02, take it as you will.

Re: DIY TDS Meter

Posted: Fri Aug 14, 2015 3:40 am
by Creeper0629
No I can't argue that point at all my friend.at this point I agree.sometimes I can be to diy lol.love that 2nd amendment quote by the way.I'm an avid nra supporter. I feel that right has been infringed to much as it is.back to topic,I guess I felt if it would be simple enough to do it would be worth trying.but it seems you need to know your trig to do this lol.it will be a while till I buy one as cash it tight right now.such is life

Re: DIY TDS Meter

Posted: Fri Aug 14, 2015 3:41 am
by Creeper0629
No I can't argue that point at all my friend.at this point I agree.sometimes I can be to diy lol.love that 2nd amendment quote by the way.I'm an avid nra supporter. I feel that right has been infringed to much as it is.back to topic,I guess I felt if it would be simple enough to do it would be worth trying.but it seems you need to know your trig to do this lol.it will be a while till I buy one as cash it tight right now.such is life

Re: DIY TDS Meter

Posted: Fri Aug 14, 2015 3:43 am
by Creeper0629
Sorry for double post.I didn't do it