I don't use it but from the research I did when considering RO water. Its fine for the tank once mineralisedHi guys, has anyone heard of the spotless water stations? I only saw one thread on this but unfortunately it didnt answer my question. Can i use this water is a freshwater tank? Do i need to re-mineralise it?
I think you are right, and that ultrapure water is degassed.it would be impossible to produce o tds water if it was exposed to the atmosphere?
Because it talks about resistivity, we must be still talking about less than 1 microS conductivity.
After PurificationAfter purification ultrapure water within the purifier has a resistivity of 18.15 MΩ.cm and contains sub-ppb levels of all impurities except dissolved oxygen and nitrogen. As soon as this water is dispensed into a vessel in the laboratory it comes into contact with air. The oxygen and nitrogen contents do not change significantly but CO2 will rapidly be absorbed from the air; hydrogen, bicarbonate and carbonate ions will be produced and the resistivity will fall to about 1.3 MΩ.cm as shown in Figure 1. In normal laboratory practice this is unavoidable. The high conductance of the hydrogen ions means that this change only corresponds to a concentration of 0.5 mg/L CO2 in solution.
No, they don't, if you actually measure ppm TDS, but I've never had much joy with <"trying to measure TDS">. In practical terms if you have less than 5 microS (~3 ppm TDS) it is DI water.TDS is total dissolved solids, so gasses dissolved from the atmosphere don't count.
As you said in another thread the only way is to evaporate a known quantity of liquid to dryness and weigh the residue. Still a compromise because the residue has to be 'baked' at a set temperature and for a certain time (depends on the standard that is being used). A right pain to do well.actually measure ppm TDS,
While I was answering @Oldguy's question I found the figures for this:but I'd assume it would be impossible to produce o tds water if it was exposed to the atmosphere?
........As distillates are open to the atmosphere before measurements can be made, the value of conductivity is really much less (down to 10 times) than it is really measured. Any ultra pure water in contact with the atmosphere has a conductivity of 1-2 microS/cm and a pH of 5, due to the small amount of CO2 (0.5 ppm) absorbed from the atmosphere.............
A few people have dipped a conductivity meter into RO water they've got from an LFS etc. and found conductivity readings in the hundreds, presumably because the unit wasn't working and nobody had checked. The lab units are <"Veolia ELGA DI units"> and they have all sort of alarms on them should the conductivity rise.As an aside I wonder about the quality on DI water for car battery maintenance, miss real distilled water.
I think that changed with the design of still where the cooling water from the condenser kept the boiler topped up. However red tap is always slow to change. I think in the old days you had an inspection or sent a statement to the Revenue about the still type. Struct me as daft as you could buy Quickfit with no questions asked.a license to purchase a new distillation unit.
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