Pool Terms

Algaecide – A compound, usually liquid or gel, that is used to destroy algae. It works by disrupting the cell walls of the algae which allows sanitiser (eg. chlorine) to destroy it easier. Some algaecides also have algaestat properties, which help keep the algae from multiplying by keeping it in a dormant stage.

​Phosphate – What are phosphates and why are they relevant to my pool? Phosphates are the salts or esters of phosphoric acid. When present in your swimming pool they act as a food source for algae that enables it grow quickly. Phosphates usually enter the pool water through leaves, lawn clippings, fertilisers, human body wastes such as sweat and urine, and even certain pool chemicals such as stain treatments. Luckily they can be removed using phosphate remover/starver, which works by bringing the phosphates out of solution where they can be trapped in the filter and flushed out of the system.

​Multi port valve – A multi port valve is the thing with the handle that sits on top of your sand filter (the big round thing). What does it do? That’s a great question! By turning the handle to it’s different settings you basically divert the water flow from the pump through different parts of the sand filter. The “filter” setting does just that – the valve forces the water down through the sand inside the filter then out the other side, theoretically trapping any dirt/debris on the way through, resulting in sparkly clean water out the other side. The “backwash” setting reverses the flow of water through the filter and diverts it to the waste water line – the majority of the dirt/debris that you trapped in the sand on the “filter” cycle is pushed back out of the filter and down the drain. The “rinse” setting is usually used after backwashing and allows you to flush any remaining dirty water out of the top of the filter before you recommence filtration. The “waste” setting allows you to bypass the sand in the filter totally to quickly remove water from the pool – it literally goes in one side of the valve and out the other – very hand for overflowing pools and quickly getting rid of heavy sediment from the pool floor. The “recirculate” setting allows you to bypass the sand filtration process and just pumps the water straight back into the pool – it is usually used for adding different types of chemicals such as flocculant and can also be helpful with starting pumps that are difficult to prime (as the water flows through easier). The “closed” setting is just that – do not operate the pump with it set on this as it will cause damage – helpful with situations where you want to stop water flowing back through the filter, such as if the pool pump is lower than the water level and you want to empty the pump basket.

​Chlorinator – What does it do? A chlorinator produces chlorine (sanitiser) as salt water passes over the chlorinator cell. Ever had someone tell you “I don’t have a chlorine pool, I have a salt pool”? Well, there is a 99.9% chance that they are incorrect. The vast majority of salt pools have salt in there for one main reason – the salt is used to produce chlorine. The other thing that the majority of chlorinators do is to control what time the whole filtration system operates by turning the pump on and off at the set times. A common misconception about salt pools is that if the pool is going green – just throw more salt in. This is usually not the problem and sometimes the increased salinity can make the problem worse. There are many reasons why a pool can go green and you normally will need a pool professional to tell you what is going wrong.

​Peristaltic pump – these are used on acid and chlorine dosing machines. It works by using a set of small rollers to slowly squeeze the fluid through the feed tube from its drum and into the pool filtration. The rollers prevent the fluid from flowing backwards to the feed drum of its own accord, or via water pressure when the filtration is running.

Flocculant (floc) – Floc is the general description of a variety of compounds that can be used to aid in the cleaning of a swimming pool. The purpose of floc when added to water is to bind together particles that are being held in suspension (floating around and not sinking to the bottom). By making the small particles into bigger particles they eventually gain enough mass that they quickly drop to the pool floor. Once the particles have dropped to the floor it is then a relatively easy process to vacuum the sediment to waste. This is very time efficient when compared to allowing the pool filtration to slowly filter all of these small particles from the water.

Clarifier – Clarifier is the general description of a variety of compounds that can be used to aid in the cleaning of a swimming pool. Sound familiar? Clarifiers are basically a watered down version of floc. ​They help to bind small particles together enabling them to be filtered out easier (some particles are so small that they will continually pass through a filter without being trapped). There are normally other chemicals added to clarifiers which help to make the water sparkle through various processes. Why not use floc instead of clarifier then? Using floc instead of clarifier is like using a bulldozer to clean a mess up, when all you really needed was a mop and bucket. It is much stronger and you can’t put floc through your filter without quickly blocking it up – floc needs to go to waste, and clarifier can work with the normal filtration process.

​Water balance – This is so important that there’s another whole page just for it. Click here!

​Pump impeller – No need to be too technical here. It’s inside your pool pump, and it’s the bit that actually pushes the water when the pump is running. Most common issue is that it gets blocked with debris that makes it through the skimmer and pump basket system – result is that the water flow is very poor. Blockages are easily enough fixed. More serious impeller issues are uncommon.

Pump bearings – Part of the pump motor. The bearings enable the pump motor to spin freely and push water. When they start degrading the pump will start making some horribly loud noises or may even just stop altogether. Nothing you can do to stop this really, it’s in the lap of the pool pump gods.

​Mechanical seal – this seal is in the middle of your pool pump and it separates the part of your pump with water in it, from the part of your pump with the motor in it. A critical piece of equipment when you think about it. A damaged mechanical seal causes the pump to leak and will cause damage to the pump motor if not fixed. A damaged mechanical seal usually goes hand in hand with damaged pump bearings.

​Pump capacitor – just think of this as the starter motor for your pool pump. When you turn the pump on this thing starts the motor spinning.

​Cleaner diaphragm – the diaphragm is a small rubber tube inside your pool cleaner that uses the water flow through it to snap open and shut quickly. This action of snapping open and shut in quick succession is what provides the ‘clunking’ noise and motion of the pool cleaner. If a diaphragm has any type of hole or tear the cleaner will usually not move. This is because the hole prevents the diaphragm from doing the snapping action which provides motion. These are consumables and can’t be repaired – in the bin and put a new one in.

​Main drain – this is not really what you think it is. Well it is, except in reverse. The main drain doesn’t drain water out of the pool, it has the ability to let ground water into the pool when water pressure surrounding the pool is too great and there is a risk of it lifting the pool out of the ground. Basically a pressure relief valve for the area surrounding the swimming pool. Some have built in suction points in the upper part of the body that allow you to connect it to the skimmer box. It can also be called a hydrostatic valve.

​Skimmer box – The skimmer box is always in the side of the pool wall and is a rectangular opening. This is the suction point for the pump and water is pulled through here to the filtration. There is a removable basket inside to catch leaves and debris. There is also the ability to put a vacuum plate on top of it and run a suction cleaner or manually vacuum through it. Very rarely a pool may not have a skimmer box, but instead just have suction cages on the pool wall deeper in the water (usually only seen on undercover pools that don’t get leaf debris).

​Weir door – this is the flap with a float on it that is at the entrance to the skimmer box. The weir door helps to attract floating debris into the skimmer box. It does this by creating a very slight waterfall effect which in combination with the water surface tension helps the skimmer box to effectively and quickly pull floating debris in to get trapped in the skimmer basket. The float on it helps it to adjust to different water levels and also helps to stop debris floating out into the pool again when the pump shuts off. If you keep your suction pool cleaner in the pool all the time it negates this effect (which causes most of the floating leaves and debris to drop to the floor and theoretically get picked up by the cleaner).