Lime Scale on HLT

[Wynne-R]

D’ooh !

I had a sort of an epiphany last night checking the temperature on my Hot Liquor Tank. I was literally watching the lime scale on the walls go into solution. You know what it looks like when you boil out temporary hardness? Same thing in reverse.

Recently, with the help of people on this forum I have been experimenting with RO additions to much good effect. I heat my sparge water in a one gallon fryer (think 1200 watt crock pot.) It’s a continuous sparge. Well I have a thin layer of calcium carbonate on the walls from previous batches heating my tap water. Now that I'm using soft water to sparge the process is reversed.

I will acid wash the vessel and get most of it. The rest will eventually go into solution, as I’m now using soft water to sparge. Well, at least it’s soft going in. I hope you all get a laugh from my foolish mistake, and maybe people out there will closely inspect their tuns for mineral scale.

 

[mabrungard]

Lime scale isn't all that soluble, so I'm not so sure it was calcium carbonate you observed. Recognize that any of the dissolved solids in the water would form a deposit on the tank walls as the water evaporates and the solids are left to crystallize on the walls. So the deposits that you noted as dissolving were more likely to be either calcium sulfate or calcium chloride. If the water in the HLT had been properly acidified to reduce its alkalinity for sparging use, then its far less likely that carbonate would have been left in solution to make a lime scale deposit.

How mineralized is your water? Its odd that there are any deposits, but its certainly possible.

 

[Wynne-R]

Here’s what the water dept says:
pH 8.2-8.4
Bicarbonate 99-123
Calcium as CaCO3 89-142
Magnesium as CaCO3 4-8
Chloride 16-33
Sodium 14-22
Sulfate 23-36
TDS 210-245
Total alkalinity as CaCo3 99-123
Total hardness as CaCo3 85-168