It looks like two different samples of water can have the same TDS, but not the same solids. This is because TDS is not a measurement of the total solids but rather a measure of the electrical condutivity. It is apparently also true that silica content will not show on a TDS meter because silicon dioxide is a VERY poor conductor of electricity. Further the wrong resin in a DI tank will effectively remove minerals that are good conductors of electricity but do absolutely nothing for silica. So it is possible to be completely misled by your TDS meter that your tanks have taken all of the solids from your water. But if they have left the silica behind it could be deposited on the windows where it will bond. Then with repeated WFP work it will build up until it can be seen in the direct sun. Especially on the second level glass at the right angle. The easiest way to see this is to look at the second level windows in the direct sun with your thumb blocking the sun. Then look closely around your thumb at the glass. I am curious about what you all think of this.
Not to down the WFP work at all. I personally wish I could afford a Reach It pole.It is a fantastic tool! But it seems to me that we should be focused on ways to accurately measure both silica and silicates. Also we should have a secondary tank to remove silica and silicates from water for those jobs that need it.
I am most certainly in “stranger waters” here so again I am putting this out to our Forum. I understand Perry has been very focused on coming up with some truly innovative filter chemistry/technology. Maybe he would like to comment here.
I am certainly familiar with the difficulty to remove silica with RO OR DI - it is just not easy to remove.
The issue of it building up on glass, I do not buy … my reason is this :
We clean windows quarterly / bi-annually, annually, and bi-yearly as a rule… There is no 'frequency for a buildup on the glass (compared to a lawn sprinkler on every day, or kids splashing salt pool water 2 hours a day all summer …
If we cleaned windows, lets say once a week : if we can add the silica to the glass in an invisible leave-behind state, freshly there from being in solution, why would it not simply come off the glass into solution again as soon as we agitate - why would it necessitate to bond and then cumulate on the glass surface ?
These are just my thoughts, I have never studied this. I can add that water fed window cleaning is a 30 year old technology - if this point were true, we would have been aware of it from practical experience … just saying. …
Thank you for responding so quick Perry. We do agree on the difficulty in removing silica from ground water using in particular a DI resin tank. Reason being this is a “chemical clean”. RO is a different technology.
Now mineral deposits can form on glass VERY quickly. In ONLY an hour. This is not theory. I have seen it happen. And with just water. In one case it was the water that picked up minerals from the exterior of the building above the windows. No agitation of course. But how does a water spot form? From a water drop as it evaporates. Therefore if the water from a WFP was carrying a relatively high concentration of silica, that silica would be deposited on the glass once the drops evaporated. Immediately. Then they would bond. Silica spotting would be advanced or not depending on the amount of silica in the water. It wouldn’t matter whether the water was agitated or not since this action would not change the amount of silica in the water.
So. I am guessing the first thing someone would want is a special kit to accurately test the silica level in the water coming out of the tank. This would be a chemical test. Since the chemistry of the silica is first altered so it can be detected. Hmmm. I think I have just come up with an idea for a product. Then. If there indeed is a high concentration of silica it would be time to employ a different technology for adequately removing that silica. Another product!
Silica is a nasty mineral and once you know where it exists and is prevalent you have to clean windows a different method like Henry explained. Hope all our fellow window cleaners on here figure out this someday. You definitely have to have a passion for your work and learn about what is in our water and do a lot of testing and experiments to figure out what works and what does not. That is what makes a great window cleaner… Knowledge is power!! lol
Use mono bed resin di for best results in getting rid of silica. The magic ratio is 2 parts negative resin to 3 parts positive resin. Use a Hanna low range silica test to measure accurately how much silica is bleeding off.
Had this happen to me for the first time Monday on a house wash/window clean combo job. Washed the house, using the customer’s water of course, and an hour later went back with my wfp to wash the exteriors. Had white water spots everywhere that would only come off with the bronze wool.
Sorry to hear that Alex. I really hate spotting. If you get them off however don’t forget to seal up the glass with the NG1010. Then even if the homeowner hoses off their car the spots will come of much easier.
