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Spotless water stations

Ospac

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25 Mar 2021
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London
Hi 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?
 

Kevin Eades

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24 Jan 2021
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Portsmouth
Hi 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 don't use it but from the research I did when considering RO water. Its fine for the tank once mineralised
 

John q

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6 Jan 2021
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Lancashire
According to the company website its perfect for aquarium use, and the even claim 0 tds.
 

John q

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Probably need somebody like @dw1305 to educate us(me) here but I'd assume it would be impossible to produce o tds water if it was exposed to the atmosphere?
 

John q

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6 Jan 2021
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Probably yes, but I'd have thought pure water would quickly gobble up carbon, nitrogen e.t.c from the atmosphere. I have been know to be wrong of course 🙃

Either way it sounds like it would be beneficial as ro water.
 

dw1305

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Hi all,
it would be impossible to produce o tds water if it was exposed to the atmosphere?
I think you are right, and that ultrapure water is degassed.

I was going to say that would only be the tiny proportion of CO2 that goes into solution as H2CO3 and (then H+ and HCO3-) that would go into solution as ions and that you would measure with a conductivity meter.

This is what the <"Veolia ELGA website says">:

After Purification

After 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.
Because it talks about resistivity, we must be still talking about less than 1 microS conductivity.

cheers Darrel
 

Oldguy

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27 Aug 2018
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401
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Gloucestershire, UK
actually measure ppm TDS,
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.

All very academic to our requirements to keep fish and grow plants.

As an aside I wonder about the quality on DI water for car battery maintenance, miss real distilled water.
 

dw1305

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Hi all,
but I'd assume it would be impossible to produce o tds water if it was exposed to the atmosphere?
While I was answering @Oldguy's question I found the figures for this:
........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.............
As an aside I wonder about the quality on DI water for car battery maintenance, miss real distilled water.
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.

The advantage of distilled water is that it is always a known entity, because steam distillation doesn't have many moving parts (just the steam really).

We still have some stills plumbed in, (like <"the one below"> ) but we don't use them any more.

Biostill-204_600x600.jpg


When we used distilled water, rather than DI, the water used to have a slightly higher conductivity , partially because the tap water is very hard (about 18dKH and 650 microS) and you only need very minor contamination to increase the conductivity. We used to get through a lot of acid cleaning the still up every week.

We also used to get through a few stills because the water pressure wasn't very consistent and if pressure dropped enough the cooling water wasn't sufficient to avoid breaking the glass. The other problem is that you need (used to need?) a license to purchase a new distillation unit.

cheers Darrel
 
Last edited:

Oldguy

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a license to purchase a new distillation unit.
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.
 
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