Almost all hot tub water care programs include some form of
scale and stain control. This protection
is important for the protection of heaters and surfaces of a hot tub. However evidence is accumulating that suggest
this very protection can add to the risk of scale formation. The risk starts
with scale and stain products that contain polyphosphonates (HEDP). HEDP is found in a majority of these control
liquids.
We require some calcium on our spa water to control
aggressive water leading to equipment failure (including plastics), and
uncomfortable conditions for soakers.
There are products that are designed to remove calcium and replaces the
calcium with synthetic product that protects the spa surfaces. These products also contain large amounts of
polyphosphates.
Scale forming in a hot tub was most commonly identified as
calcium carbonate formed when the calcium in the water combines with
carbonates. The resulting calcium
carbonate is less soluble in hot water and begins to precipitate out. We now recognize that scale can be calcium
phosphate formed when orthophosphates combine with calcium resulting in calcium
phosphate scale, also insoluble in hot water.
Many of us are familiar with phosphate as a promoter of
plant growth and in the absence of
proper sanitizer can promote algae growth.
Phosphates are also a major pollutant to our water systems (rivers and
lakes) and should be removed from our hot tub water before draining.
Prevention is the key.
1. Depending on the style of spa treatment you are running,
use non-phosphate metal and scale treatments (Dazzle's Stain'n Scale 1 and 2,
Mineraluxe are good examples of these new non-phosphate products).
2. Have your water regularly tested for phosphates and
maintain levels below 100 ppb.
3. If your phosphate levels exceed 250ppb use a phosphate
cleanser (remover) to lower your levels.
THis should be done anytime levels are high an d when draining your spa
if your phosphate levels are above recommended levels.
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