How to Vacuum a Pool with a Sand Filter - Settings and Steps

Filter vs Waste: The Most Important Decision

Before you pick up the vacuum pole, you need to decide which multiport valve setting to use. Getting this wrong wastes your time and leaves the pool cloudy.

Use FILTER when:

• Vacuuming normal dirt, leaves, sand tracked in by swimmers, general debris
• The pool is clear and you are doing routine maintenance
• You want to conserve pool water

Use WASTE when:

• Vacuuming a visible algae bloom or dead algae after treatment
• Vacuuming very fine silt or dust that tends to pass straight through sand
• Vacuuming up sand that has returned to the pool from a filter issue

The key difference: on FILTER, the water passes through your sand and returns to the pool. On WASTE, the water exits directly through the backwash line and leaves your pool. You lose water on WASTE - have the hose ready to top up.

Why Algae Requires the WASTE Setting

Sand filters are designed to trap particles 20-40 microns in size. Algae cells are 2-10 microns. When you vacuum dead algae through a sand filter on FILTER mode, a significant percentage of the cells pass straight through the sand and return to the pool via the return jets.

The result: you vacuum for 30 minutes and the pool looks the same as when you started, because you are returning as much algae as you are removing.

Use WASTE when treating algae. Yes, you lose pool water - typically 6-12 inches over a full pool floor vacuuming session. That is far better than recirculating the algae you are trying to remove.

Priming the Vacuum Hose - Why It Matters

Air in the vacuum hose breaks the suction. You will move the vacuum head across the floor and pick up nothing because there is no vacuum seal.

Priming removes the air before you connect to the skimmer:

1. Hold one end of the hose over a return jet so pool water flows into it, or
2. Submerge the entire hose in the pool and hold it under until all bubbles stop

With the hose full of water (dripping from the free end), quickly insert it into the skimmer inlet. The pump maintains suction as long as no air breaks the seal.

If you lose suction mid-vacuum (usually from lifting the vacuum head out of the water), you need to re-prime.

Vacuuming Above-Ground Pools

Above-ground pools with sand filters work identically but often require a vacuum plate adapter for the skimmer. Standard above-ground pool skimmers have a circular opening that the vacuum hose end does not fit tightly without the adapter.

The adapter is a flat plate with a hole sized to your hose, designed to sit over the skimmer opening and create a proper seal. Without it, air leaks around the hose and breaks vacuum.

Pool vacuum plate and hose kits on Amazon

Backwash After Every Vacuuming Session (FILTER Mode)

After vacuuming on FILTER setting, your sand has loaded with everything you removed from the pool floor. Always backwash and rinse after vacuuming to clear the filter and restore normal flow.

Skip this step and the filter runs at elevated pressure for the next few days - reducing filtration efficiency and causing your jets to run weaker than normal.

Related Guides

• How to Backwash a Pool Filter - post-vacuum backwash procedure
• What Does Recirculate Do on a Pool Filter? - all multiport valve settings explained
• Pool Filter Pressure Too High - if pressure stays high after vacuuming
• Sand Filters Complete Guide - all sand filter topics