Sand Filter Purge

Dosing based on one Pentair TR-140 commercial sand filter

Sand Filter Purge PDF

Overview

Have you ever been told that filter sand "wears down" and needs to be replaced after a certain number of years? That seems to be the industry standard explanation to justify costly filter sand replacements, but we don't buy it anymore. We went into a YMCA with 11-year-old sand in it, and we chemically purged it. After just 4 hours and two backwashes, we could not tell the difference between the chemically-refurbished sand and brand new sand. The customer saved thousands of dollars because they did not need the sand changed, and their filter is working great.

Related: How to Implement the Orenda Program

You will need:

• PR-10,000
• CV-600
• Stirring object (or air pressure wand)

Phase 1: Chemicals

1. Turn pump off, isolate the filter and open up the lid.
2. Lower the water level in the filter to about 2-3” above the sand.
   • Collect a handful of dirty sand for before-and-after samples (optional).
   • Remove large physical debris (if applicable) prior to adding chemicals
3. Add one quart (32 oz.) of CV-600 enzyme and 8 oz. of PR-10,000 phosphate remover to the filter.
4. Stir and mix chemicals deep into the sand bed as thoroughly as possible.
   • We recommend an air compressor with a long wand. If that is unavailable, use a garden hose, broomstick or something similar to allow chemicals to soak deep into the sand bed.
5. Start a timer for a minimum of three hours (the longer, the better). Leave the filter lid off during the wait.

Phase 2: Backwash and Rinse

1. After at least three (3) hours, close the filter lid and backwash.
2. After backwashing, turn pumps off again, open the filter and inspect sand.
   • Collect a handful to compare sand before-and-after (optional).
   • If the sand filter is not to your satisfaction, repeat this step after the second backwash.
3. Close filter again, and backwash for a second time. This step is very important, make sure you backwash again!
   • The first backwash lifts most of the organics out of the sand, and causes suds and foaming. The second backwash flushes all of that out of the filter to waste.
4. After the second backwash, run the rinse cycle thoroughly.
5. After rinsing, resume normal operation with your newly cleaned sand filter.

Additional information

For larger filters, extrapolate dosing at teh same 4:1 ratio of enzyme to phosphate remover (CV-600 : PR-10,000).  For example, large commercial filters may take an entire gallon of PR-10,000 and up to 4 gallons of CV-600. The 4:1 ratio is important for this procedure to work properly. If you want Orenda’s help, contact us directly. We’re happy to walk you through it.

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