Quote:
Originally Posted by jeffba
Calcium build up in the water heater can cause the water to develop a rotten egg smell. It is a bit of work to clean it out.
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Actually Calcium Carbonate (CaCO3) is not the source of "rotten egg" smell. CaCO3 deposition is more likely with temperature rise (contrary to most other mineral scales) so that is the reason you so often see it in hot water tanks. Pure CaCO3 will have a white appearance and look somewhat like concrete. It is acid soluble and brittle.
The "rotten egg" smell is Hydrogen Sulfide gas. That is the result of microbiological activity. Specifically Sulfate Reducing Bacteria. Or it can be the result of Pyrite dissolution in the producing formation (very unlikely in a fresh water source). In the case of your hot water heater, you are giving the SRB bacteria a stagnant warm location that is ideal for their reproduction. If the water is stagnant for extended time frames, even better for them. H2S in the water can lead to the formation of black sludge or scale in the presence of Iron (either in the water or from plumbing) composed of Iron Sulfide. That scale is also acid soluble and brittle. Best treatment in that case is to kill the bacteria with chlorine and thoroughly flush the system.
It should be specifically noted that if you have H2S in your FRESH WATER system it has been contaminated with bad water!! Fresh water systems should have been treated such that there isn't a sufficient level of bacteria to reproduce (unless they are left stagnant for a very long time, even then they need a source of contamination to start the process)! Contamination with Oxygen is not an issue as SRB strains of bacteria are Anaerobic (IE: they do not require Oxygen to live).
You may see a combination of both types of scales in your tanks. If you can't flush it out with water and or lightly tapping on the walls of the metal tank itself then as a last resort you can try softening it with Hydrochloric Acid (Muratic Acid at the hardware store) but that risks degrading the tank integrity as the acid is also corrosive to metal tanks.
I don't have the issue but did make flushing nozzles out of 3/8" SST tubing which I bent such that the pressure wash is directed back toward front of tank on one of the pieces of tubing. On a second piece it is straight such that I can flush the back of tank. Wisdom would suggest that any tool you stick into the water system should first be treated for bacteria by dipping in solution of chlorine and the system should be very thoroughly flushed afterwards.
It should be noted that a filter is unlikely to stop either form of scale and in fact if left static a filter bowl is another prime location for bacteria to grow. The micron size filter that can capture bacteria would restrict flow severely. The components of a mineral scale (in this case, Ca and Bicarb) will pass right thru a filter if they are still soluble and do not form the scale until they see a pressure drop or temperature increase. A water softener may stop CaCO3 precipitation downstream (via Ion Exchange) but does nothing for bacterial activity and again could be a location for bacterial bloom if left stagnant for an extended timeframe if the source water is contaminated.
Sorry guys this is what I do in the oilfield........