Pool Filtration: Why variable speed pumps are worth it.
Over many years the art of calculating flow and filtration rates has been lost. Many pool engineers now guess what size filter and pump are required, but not here at Specialist Pools Services. Turnover rates (the time taken for the volume of the pool to pass through the filter) are set out by the pool industry governing bodies, but the filtration rates of domestic pools are rarely discussed. By lowering the velocity of water flowing through a filter, it will improve water clarity.
The analogy we at Specialist Pools Services like to use is, on a sandy beach, if you have a grain of rice and a bowling ball, they will both sit on the surface, you can push the grain of rice into the sand but not the bowling ball, but with enough pressure the bowling ball can be pushed under too. These principles are the same for filtration, by putting a bigger filter on the same pool system, you are lowering that pressure inside said filter and allowing more to sit on the surface. In a filter, we are talking about microscopic particles, so the tolerances are much more delicate. All this being said, adding a variable speed pump to your pool with a flow meter allows you to balance the flow with the filtration very accurately.
Now for the other way, backwash. Backwashing needs to take place at a higher velocity than filtration. Trying to filter water through a dirty filter is like washing the dishes in greasy water, it’s not going to work. Increasing the velocity during backwash will fluidise the filter media, this is achieved by increasing pump speed. When the media is fluidised, it will allow the media to move around, and the particles that were once trapped by the media will go to waste cleaning your filter for the next filtration cycle. Going back to the washing plates, you’ve changed the water.
Another advantage of a variable speed pump is cost saving. Why run the pump at full speed when the pool is not in use? We have already mentioned that slower filtration gives cleaner water, so this will allow your pool to recover while not in use, the pump will use considerably less power (80% pump speed will use 50% less energy) when turned down and with less water movement the heating system will not be required to work as hard during these slower times.
Don’t hesitate to use our contact form, via the button above, if you would like to discuss any of these points further, to ensure every inch of your pool is perfect from the bottom to the top.
