Domakihub Vacuum Dead Algae to Waste and Stop It Coming Back
Why the "waste" setting on your multiport valve is the only safe way to remove dead algae from your pool.
Reviewed by Domakihub pool pros · 2026-06-23 · 5 min read
After a shock treatment, a pool that looked green can turn an uninviting grey-white haze — that is dead algae, and it needs to come out completely before your water clears. The video above demonstrates the vacuum-to-waste process in real time; this guide walks through the exact steps and explains why doing it any other way will leave you starting over. Whether you manage a private home, a holiday villa, or a hotel pool in Greece, getting this step right saves you chemicals, time, and frustrated guests.
Why Dead Algae Defeats a Normal Filter
When you shock a pool, the chlorine kills algae cells but does not remove them — it just bleaches and breaks them down into microscopic particles. Those particles are so fine that a standard sand filter cannot trap them reliably. Vacuum on the normal 'filter' setting and the cloudy water simply gets pushed back into the pool through the return jets, re-suspending everything you just tried to remove.
The multiport valve's 'waste' position routes water directly out of the pool and through the backwash line, bypassing the sand bed entirely. Nothing goes back in. This is the only setting that physically removes the algae debris from the system rather than recirculating it.
When to Vacuum — Timing It Right
Vacuum too soon after shocking and the algae particles are still suspended in the water column; they will drift away from the vacuum head and you will chase them endlessly. Wait until they have settled on the floor of the pool — usually 8 to 24 hours after the shock dose, depending on water movement and temperature. In Greek summer heat the settling time is often shorter because warmer water speeds up the die-off.
Check the floor before you start. If you can see a visible grey or white sediment layer on the bottom, you are ready. If the water column is still uniformly cloudy, run your pump on filter for another few hours and check again.
How to Vacuum Dead Algae to Waste: Step by Step
- 1
Top up the pool water first
Vacuuming to waste sends water straight to drain, so your pool level drops fast — sometimes 5 to 10 centimetres in a single session. Fill the pool to the very top of the skimmer mouth before you begin. This gives you a buffer and ensures the pump never runs dry, which can damage the seal.
- 2
Set the multiport valve to 'Waste'
Turn the pump off completely before touching the multiport handle — rotating it under pressure cracks the internal spider gasket, an expensive repair. With the pump off, move the handle firmly to the 'Waste' position. Double-check the label; on many valves 'Waste' and 'Backwash' are adjacent and easy to confuse.
- 3
Prime and connect the vacuum head
Attach the vacuum head to the telepole and connect the hose. Before plugging the hose into the skimmer, submerge the entire hose length to purge all air — hold one end over a return jet if your setup allows it, or feed the hose under water hand-over-hand. An air-locked hose will break suction mid-vacuum and stir up the settled debris.
- 4
Move slowly across the pool floor
Turn the pump on and begin vacuuming from the far end, working methodically toward the skimmer end in overlapping parallel strokes. Move the head slowly — roughly half the speed you think you need. Rushing lifts the sediment back into suspension. If a cloud rises, stop, let it re-settle (5 to 10 minutes), and continue.
- 5
Backwash, rinse, and rebalance before you finish
Once the floor is clear, turn the pump off, switch the valve to 'Backwash' and run for two minutes to flush any residual debris from the sand bed, then switch to 'Rinse' for 30 seconds to resettle the sand before returning to 'Filter'. Top up the water level again if it dropped, then test and rebalance your pH and chlorine — the large volume of water removed during vacuuming will have shifted your chemistry.
Rather have a pro handle it?
Get a vetted pool pro in your city — one number, booked in EN/EL/DE.
FAQ
- Can I vacuum dead algae on the 'filter' setting if I add a clarifier first?
- A clarifier helps clump fine particles so the sand can catch them, but it is still unreliable for a heavy algae die-off. You may need multiple backwash cycles and still end up with hazy water for days. Vacuuming to waste is faster, more certain, and uses less chemicals overall — the extra water top-up cost is minimal compared to another round of shock and clarifier.
- How much water will I lose vacuuming to waste?
- It depends on pool size and how long you vacuum, but expect to lose 2 to 5 percent of your pool volume in a typical session. For a 50 m³ villa pool that is roughly 1,000 to 2,500 litres. Always fill to the top of the skimmer before starting and check the level mid-session if you are dealing with a severe algae bloom that requires multiple passes.
- My pool is still cloudy after vacuuming to waste — what did I go wrong?
- The most common cause is vacuuming before the algae had fully settled, which stirred the particles back up. The second is moving the vacuum head too quickly. Let the pool sit without any water movement for 12 hours, then vacuum again in slow, deliberate passes. If cloudiness persists after a second attempt, test your water: low free chlorine means the algae may not be fully dead yet and you need another shock dose before vacuuming again.