How to Soften and Remove Scale in a Swimming Pool or Spa
Scale Removal with LSI balance and SC-1000
Based on 10,000 gallons (37,855 L)
Overview
Calcium carbonate scale is the consequence of water being over-saturated with calcium carbonate. Calcium carbonate saturation equilibrium is measured using the Langelier Saturation Index (LSI). Scale begins to form when the LSI is higher than +0.30 (+0.31 and above). On the Orenda Calculator, the LSI will be purple.
To remedy this, the LSI needs to be placed in a safe, but slightly-negative place (-0.30 to -0.01), to allow for the calcium to be brought back into solution. On the Orenda Calculator, the desired LSI for this procedure should be yellow.
Scale, especially on tile lines, is often compounded by organic waste that makes it difficult to clean off. We recommend a combination of both SC-1000 to break down and dissolve the calcium carbonate, and CV-600 enzymes to break down and remove the organics.
Related: How to Implement the Orenda Program
You will need:
- A clean bucket
- SC-1000
- CV-600
- Acid
- Reliable test kit
- The Orenda Calculator
Day 1
- Raise the water level and/or turn on water features to soak the scaled area(s).
- Test the water chemistry, and input it into the Orenda Calculator under “current levels”.
- On the right side of the calculator (desired levels), adjust the pH to 7.2-7.4, and find a way to get the LSI between -0.30 and -0.01. The LSI number should be yellow.
- Pour the prescribed amount of pre-diluted acid evenly around the perimeter of the pool.
- Add one quart (32 fl.oz.) of CV-600 or CV-700 directly into the skimmer.
- Add one quart (32 fl.oz.) of SC-1000 directly into the skimmer.
- SC-1000 will deplete chlorine levels with the initial purge dose! Manually feed chlorine after a day or two until chlorine levels are restored. SC-1000 just needs time to bind to metals and minerals. The colder the water, the longer the chlorine will be neutralized.
- You can also opt to divide this purge dose of SC-1000 into multiple visits. It will take longer to remove the scale, but you are less likely to wipe out chlorine entirely.
Following Visits
- If the scale is still there, rub it with your fingers to see if it has softened or loosened. Brush and clean physically, avoiding abrasive tools that can scratch the tile.
- Re-test the water chemistry each visit, and document the results in the Orenda Calculator.
- pH will naturally rise over time, so be sure to account for that in your strategy. You should contain pH with a lower carbonate alkalinity and enough calcium hardness to offset it on the LSI.
- Adjust the water chemistry to be back in the yellow LSI range of -0.30 to -0.01.
- Apply maintenance doses of both CV-600 (5 fl.oz./10,000 gallons) and SC-1000 (3 fl.oz./10,000 gallons) directly into the skimmer.
- Add chlorine, as SC-1000 may have still impacted the levels.
- Maintenance SC-1000 dosing should not impact chlorine levels noticeably.
- Repeat the process on each visit until the scale has been removed.
Additional information
This process generally takes 2-3 weeks. SC-1000 gently breaks down the carbonate scale, unlike acid. It needs time, and the water must be maintained in a slightly negative LSI state to dissolve the calcium. Always measure doses of chemicals and use proper safety gear.
More Questions?
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