Join Date: Dec 2012
Location: NE of Youngstown, OH
Are silicates still high after you mix your hot tap water with your cold RO water?
Volume of water is pretty high. I was gonna suggest boiling some of the RO water but I bet you'd need to boil 5+ gal this time of year to get up to temp. Easily done with a turkey fryer or if you happen to be a homebrewer. Otherwise it's just a complicated and equipment heavy option.
Phosphate removal resins take out silicates but your also taking out, well, phosphates. They typically go in a media bag or reactor. Maybe run phosguard until silicates are gone, turn it off, and then dose phosphorous. I don't know if phosguard is fast enough but maybe you could even run right out of the tap, through a reactor or water filter housing.
I think letting your furnace heat it over a day or 2 is the way to go. A 20% water change with 78F tank water and 68F fresh water only drops your tank to 76F. If that's too much for you, let your furnace warm it then turn on a heater to bring it up the last bit.