Made another batch of clear ice and melted it. Ended up about a litre. This time i took care to let the ice melt a bit so as to reduce any contamination with cloudy ice. It's easy, just let it sit out and shave away towards the clear part. Rinsed out the container it would melt in as well and hit zero TDS
What is zero TDS and did i really make zero TDS water ? well, not quite. Technically, zero TDS means water with a
conductivity of 0.05 micro siemens. This is ultra pure water. So what is the conductivity of my water.
2.1 micro siemens. So zero TDS is 42 times purer.
And what about the TDS
0.9 TDS
This
meter has more resolution, adds a decimal point. The cheaper ones round down anything that is less that 1.00 TDS as zero. They do whole numbers only so aren't sensitive enough below 1 TDS.
I
tested the total hardness in CaCO3 and it worked out to 1mg/L or 1ppm.
Starting from aquaguard water of TDS 145 and total hardness somewhere between 125-150 mg/L (ppm) of total hardness down to 0.9 TDS and 1mg/L total hardness. This is pretty good for a home effort i'd say.
I went looking for distilled water again and picked up a 1L & 5L from an Indian Oil petrol bunk. Last attempt from BP petrol bunk was a reject, so will this brand be better ?
Looking at the label, this Indian chemical company shows more info. Says they've been in the business since 1988, that's got to count for something.
Not only is there a manufacture date, there is also a best before date. Unlike the last product, this company states their water is only good for a year from manufacture. They also state their water is zero TDS and de-mineralised. No idea what free "chlofine" is, chlorine maybe, but i'd have liked to have seen nil for chlorides. No idea what unit they are using when they say less than 20. If there are any Chlorides then should get picked up by the meter as they will increase TDS. Chlorides should not exceed 5 ppm or there will be loss of capacity in both plates with the positive losing more.
They state the electrical conductivity is 4 micro ohm/cm which is the incorrect unit for conductivity. Conductivity is not expressed in ohms/cm but siemens/cm. Resistance is expressed in ohms. Since 4 mico ohms is mighty low it must be 4 micro siemens. Purer water has higher resistivity and is the reciprocal of conductivity. So how does this one test out ?
TDS 1 says the AP-1, actually its 1.4 says the other. So any TDS under 1.5 i'm guessing gets rounded down to 1 on the AP-1. The conductance is 3.1 uS so that is within spec. The total hardness is zero.
Compared to the last bottle i got this one is way better.
It has less hardness than my clear ice sample but i got it beat for TDS & conductivity.
Conductivity seems a more sensitive way to measure water purity than TDS at near zero TDS.
EC is the norm in the EU. The Americans use TDS and complicate things. TDS can use different standards, 442, NaCl & KCl. Unless the specific std is mentioned a TDS count is meaningless. EC is simpler and does not depend on anything else. TDS is EC times some factor.
The setting of 0.5 refers to NaCl standard. If a TDS meter goes up to 5000 ppm like the AP-1 then its using the NaCl standard which has a 0.5 conversion factor between conductivity & TDS. With HM meters conductivity is roughly twice TDS.
Is there a correlation between TDS & hardness? Samples i've tested show a close correlation until they don't. Last sample of distilled water i got had a TDS of 23 but total hardness was 2 mg/L. So TDS & Hardness are not always fully equivalent. There could be other things in the water contributing to TDS but not coming from hardness.
Still on the lookout for Exide distillo, no exide care nearby had it.
Want to try deionised water as well if it can be had at a decent price.