March 28, 2024, 11:19:35 AM
Forum Rules: Read This Before Posting


Topic: Silica in domestic water conundrum  (Read 2169 times)

0 Members and 1 Guest are viewing this topic.

Offline lindmcc

  • Very New Member
  • *
  • Posts: 1
  • Mole Snacks: +0/-0
Silica in domestic water conundrum
« on: May 28, 2017, 01:21:37 AM »
We have a new domestic water system taking bore water for our new house. We have silica being deposited on benches, sinks, basins & baths. We tracked it to hot water via the water test below. Supply water flows through a particulate filter, coarse salt filter (Kinetico) then another particulate filter before going to the hot water cylinder or cold water system. The hot water cylinder is also heated by a solar system, power and heat pump. The cylinder is a Greenglo 500D which is vitreous enamel lined with a magnesium anode.

Parameter:                           Before Softener:   After Softener:        Hot Tap (after softener):
pH (SU):                           7.3                   8.0                        9.8
Total Dissolved Solids (mg/L):   110                   120                        240
Alkalinity (mg/L):                   60                   -                        -
Total Hardness (mg/L):           80                   <5                         <5
Silica (mg/L):                   14.5                   15.5                        111
Total Iron (mg/L):           0.05                   0.02                        0.03
Manganese (mg/L):           <0.01                   0.02                        <0.01
Langelier Index:                   -1.1                   -                        -
Turbidity (NTU):                   0.26                   0.52                        0.74
Colour (˚H):                   <1                   <1                        <1
%UVT @ 254 nm:                   97.8                   97.1                        77.5


Does anyone have any ideas where the extra silica is coming from in the hot water system?

I have read that, 'Colloidal silica will show up very little even in the chemical test, as it is a polymer and quite unreactive. Once it goes into a boiler, it is hydrolysed under high temperature and high pH of the boiler water and appears as if by magic, as suddenly it is monomeric and able to react with the test method.'

Could this be the reason for the much higher silica test reading from water taken from the hot tap?
How high does the temperature have to be to hydrolyse the silica?
Is there another explanation?
How do we treat the water if the true silica level is 111 mg/L?

Does anyone know how to remove silica scale from enamel baths, porcelain basins & stainless steel without damage?

Sponsored Links