Here’s How to vacuum a pool to waste with a sand filter

Sometimes a swimming pool gets overwhelmed with leaves, algae, and debris on the bottom, which the standard automatic pool cleaner can’t cope with. Or we have a time constraint in which the pool needs to be cleaned. In this post, we will be discussing which is the correct multiport valve position to use when vacuuming a pool with a sand filter.

You don’t want all of that debris to pass through the sand filter and clog it up. Firstly switch off the pool pump. Both the weir and pool pump baskets must be removed, cleaned and refitted.

Just to make sure that they are not already blocked which could cause a restriction in water flow when vacuuming. Check to see that the swimming pool water level is at least half the height of the weir opening. The vacuuming process uses a lot of water.

The Multiport valve has six positions. Filter, Rinse, Recirculate, Backwash, Waste and Closed. Because there is a lot of debris sitting on the bottom of the swimming pool the multiport setting must be on WASTE.

Remember to push down on the handle before turning it to the Waste position.

When the Multiport valve is in the waste position the dirty swimming pool water is going to bypass the sand filter and flow straight out the waste outlet pipe into the garden or drain.

If the Multiport valve is in either the Filter, Recirculate or Backwash position all the debris that is being sucked up from the bottom of the swimming pool will be passing through the sand filter and back into the pool.

The sand filter will quickly get clogged and the smaller debris particles will be pumped straight back via the return jets straight back into the pool. This is a situation you do not want.

Connect the weir cover and pipes to the manual vacuum unit. Switch on the pool pump and continue vacuuming. When vacuuming is completed switch off the pool pump.

Remove and re-clean the weir and pool pump baskets. Replace the baskets. Check the swimming pool water level and fill if necessary. Test and correct the PH and chlorine levels after filling the swimming pool.

Reset the Multiport valve to filter for normal filtration.

How To Clean The Sand Filter In Your Pool

Backwashing a swimming pool sand filter is an important element of pool maintenance. It ensures that swimming pool water is filtered correctly at all times. A sand filter needs to be back-washed once every 2 weeks or when the automatic pool cleaner moves slowly around the swimming pool.

How do swimming pool sand filters work? 

Before learning how to backwash the sand filter, let’s first get to know its main element and how it works. 

Sand as the filter medium:

This natural element has a great capacity to filter water. Today it is the filter medium most used in swimming pool filters and thanks to them the water remains impeccable. 

A Fact to remember: This filtration method is one of the most effective.

How do sand filters work?

  • They transfer the water through the filter distributor from the top to the bottom. 
  • They trap all dirt and any impurities present within the water, due to the small sand particles that the sand is made up of.
  • As the filtration cycle continues, little by little more contaminants are deposited between the sand particles.
  • Finally, when the water entering the filter reaches 10 pounds compared to the water leaving the filter reaching 20 pounds, it is then time to backwash the filter. This difference in pressure can be noticed when observing the pressure meters located on each side of the filter inlet and outlet pipes.

Another fact to remember: The average life span of sand filters are 5 to 15 years.

How To Clean Your Sand Filter

1] Switch off the swimming pool pump motor.

2] Disconnect the automatic pool cleaner or anything else that is connected to the pool weir.

3] Remove and clean both the weir and pool pump baskets. Refit baskets back into place.

4] Set the multiport valve onto the BACKWASH position. Remember to push down on the multiport handle first to unlock it before turning the handle. This prevents the multiport valve seal from being damaged.

5] Check to see that the waste hose is laying in the correct place, as this is where all the dirty water from the sand filter is going to. Also to make sure that the dirty water is not returning back into the swimming pool.

6] Switch on the swimming pool pump and allow it to run for at least 2 minutes or until the water in the sight glass is clear.

7] Switch off the swimming pool pump motor again.

8] Push the multiport handle down and turn it to the RINSE position. This is to recompact the loose sand after the backwash cycle.

9] Switch on the swimming pool pump for 20 seconds.

10] Switch off the swimming pool pump again.

11] Push the multiport handle down and turn it to the FILTER position.

12] Reconnect the automatic pool cleaner to the weir and resume normal filtration and cleaning.

As you can see, sand filters are important regarding pool filtration to be taken care of so your pool can be kept impeccable at all times.

For this reason, it is essential to ensure that the filter is always in optimal condition, and it is very important to clean it regularly. 

Also, doing a backwash to the filter of your pool is not a complicated task nor does it take up much time.

So now that you know how to clean a pool filter, all you have to do is make your pool crystal clear and enjoy it.

How To Raise Low Chlorine Levels In Your Pool

Maintaining the correct Chlorine level in a swimming pool is important. If the level drops too low then there is a possibility of Bacteria and Algae Growth in the water.

The correct level of Chlorine in a residential swimming pool should be between 1-3ppm.

If the level is below 1ppm then there is no sanitizer to fight and prevent bacterial growth, which gives the swimming pool a greenish color and is unsafe to swim in.

How To Raise Low Chlorine Level In Your Pool

A thorough clean out of the pool pump basket and weir baskets, a thorough brushing of the swimming pool walls, steps, ladders, and the floor is necessary to get the dirt and bacteria mixed with the water.

Remove leaves and heavy dirt from the pool bottom. Then backwash the pool for 2 minutes and rinse for 20 seconds. This will clean the filter sand, so it is ready for the main filtering of the dirty water.

Then test and correct the PH level of the swimming pool water. The PH level for a Marbelite Pool should be between 7.2-7.6 and a Fiberglass Pool 7.0-7.2.

If the PH level is less than 7.2 in either a Marbelite or Fiberglass Pool Add HTH Soda Ash.

If the PH level is greater than 7.6 in either a Marbelite or Fiberglass Pool Add HTH Easy Acid.

When the PH level is correct then it is very important to also check and correct the Total Alkalinity of the swimming pool water. Total alkalinity is measured by its concentration in parts-per-million (ppm), and the ideal range is between 80-120ppm.

If the Total Alkalinity is low then Add HTH Alkalinity Up. 1kg of HTH Alkalinity Up should raise the Total Alkalinity by approximately 10ppm.

If the Total Alkalinity is high then Add HTH Dry Acid/Easy Acid. Never add more than 250g of HTH Dry Acid/Easy Acid at any one time.

With both the above levels corrected. HTH Granular and Mineral soft can now be added to the swimming pool water. If the pool water is excessively green and it has a sign of green algae then HTH Shock It can be used instead of or with the HTH Granular.

With the pool pump on and set on filter. Add 3 x the normal dose of HTH Granular plus 1 bag of HTH Shock It. Or just add 1 bag HTH Shock It. Add these chemicals around the sides of the pool in the early evening.

Test and correct the PH levels every 12 Hours until the swimming pool water is clear and the Chlorine Level is between 1-3ppm.

How To Get Rid Of Green Algae In Your Pool

Green water or floating green algae in a swimming pool is a common problem. Several chemicals can be used for treatment. By regular swimming pool maintenance, you can prevent green algae from returning.

How To Use Chlorine To Kill Green Algae In Your Pool Water

If your swimming pool water contains clumps of visible green algae, then there isn’t enough chlorine in the swimming pool. “Shocking” the swimming pool with chlorine is the most effective way to kill existing green algae and bring your swimming pool back to life.

Usually, this works within a time period of 1–3 days, but if the swimming pool conditions are poor, it could take up to a week.

How To Remove Green Algae From The Pool Walls


Brush the swimming pool walls and floor. Remove as many green algae as possible. This will reduce the time needed to kill and clear the green algae.

Pay particular attention to the swimming pool steps, ladders, and other areas where algae tend to form.

Make sure that the brush matches your swimming pool. Steel brushes work well for concrete swimming pools, while for vinyl and fiberglass swimming pools nylon brushes are preferable.

Test The pH Level Of The Water


Balance the pH by adding either an acid or a base to bring the level to just around 7.8 before treating the pool. This is at the high end of the range that you would normally have in your pool, but when you treat it for algae, it is necessary as this increases the efficiency of your chlorine and therefore reduces the growth of green algae.

Here’s how to balance the pH level: Turn on your swimming pool pump to circulate the chemicals throughout the pool. Correct the pH level either by increasing the sodium carbonate pH or by lowering it with sodium bisulfate.

It’s more accurate to use test kits that have tablets or droppers than paper test strips. If the pH levels return to normal but total alkalinity exceeds 120 ppm, check the instructions on the pH reducer label (sodium bisulfate) to reduce the total alkalinity to between 80 and 120 ppm.

Choose a suitable chlorine Shock product. Do not use the chlorine that is used for regular swimming pool treatment. Ideally, liquid chlorine for swimming pools should be used. Sodium hypochlorite, calcium hypochlorite, or lithium hypochlorite should be included in the product.

If you have hard water, avoid calcium hypochlorite.

Avoid granular or tablet chlorine products that contain large quantities of stabilizers that should not be added to the pool. Check the product for instructions on how much to use.

Use twice the recommended amount to fight green algae for a regular shock. Use triple the amount if the water is green with thick suspended algae, or even quadruple if the steps are not visible. Add the shock directly to the swimming pool edge with the swimming pool pump running.


Because UV rays break down chlorine in sunlight, add at night as this is when the chlorine is most effective.
Before switching the pool pump on, make sure that the weir basket and pump filter are clear of all debris. If not this will lengthen the filtering process of the green algae.

Check the swimming pool after the pool pump has run for 12–24 hours.

Dead algae turn’s white or gray, either the algae are suspended in the water or it settles at the bottom of the swimming pool. Remember to vacuum the dead algae from the swimming pool floor.

When vacuuming, make sure that the multivalve is on backwash so it does not block the filter. It is advisable to reclean the weir and pump filter after 24 hours as green algae will now be trapped in these parts.

Whether the green algae is dead or not, test the swimming pool water for chlorine and pH levels.

If the level of chlorine is higher (2–5 ppm) but the green algae is still there, keep these levels constant for the next few days. If the chlorine levels have risen but are still below 2ppm, then the next evening “Shock” for a second time.

If the chlorine levels have not changed significantly, your swimming pool is likely to have too much cyanuric acid (over 50 ppm). This comes from using granulated or tablet chlorine, and your chlorine condition can be “locked”.

The only way to fight this is to repeatedly “Shock” or partially drain the swimming pool.


The chlorine strength can also be used up if leaves or other unwanted dirt is in the swimming pool as well as if the pool has not been used for a long time. So make sure that the unwanted dirt is removed. It may take a full week and several “Shock” treatments for the swimming pool to come right if this is the case.


The chlorine should kill the green algae over the next few days. Test the water daily to confirm you have the correct amount of chlorine and pH. A well-maintained swimming pool has these values: free chlorine: 2-4 ppm, pH: 7.2–7.6, alkalinity: 80–120 ppm and calcium hardness: 200–400 ppm, respectively.

Small differences are common, so there should be no problem with a slight deviation.

If you still have trouble with the green algae, add coagulant or flocculant so that it clumps the algae together. Once there’s no green color left in the pool, vacuum up (set multivalve to backwash) all the dead algae until the water is clear.

You could let the filter handle it, but make sure the filter is clean first. If you do not thoroughly clean the filter, the filter can get blocked by the dead algae.

Check for the proper functioning of the swimming pools water jets.

They should point at an angle in the water so that the water moves in a spiral pattern around the swimming pool to get the most effective circulation for filtration.


Adding flocculant or coagulant is the fastest way to make your swimming pool water look good, but it’s not safe to swim in this water. Follow this with a treatment of chlorine “Shock” to sanitize the pool and do not swim in the pool until the levels of chlorine and pH return to normal.

How To Treat Pool Water With Algaecide

Algaecide will surely kill your green algae, but it may not be worth the side effects and expenses. Some algaecide products, especially if you have black algae as well, are not powerful enough to treat an existing problem.

Ask a pool store for help, or find a 30 percent + active ingredient product.


Quaternary ammonia algaecides (“poly quats”) are inexpensive but foam your water. This is annoying to many people. Algaecides based on copper are more effective but costly. They also stain the walls of your pool.

How To Remove Phosphates From Pool Water

In water, algae feed’s on several nutrients, particularly Phosphates. Phosphate test kits are available to test swimming pool water for these chemicals.

Use a commercial phosphate remover from a pool store if they are in the water. When adding Phosphate remover to swimming pool water, let the pool pump run and the water must circulate through the filter for 24 hours.

About 300 ppm is an executable level unless you have recurring problems with green algae. Then this level should be lowered.

Clear Swimming Pool Water.

Keeping Your Swimming Pool Water Clear Is Important

If you maintain your pool chemistry levels, algae should not grow. Test the swimming pool for free chlorine, pH, alkaline and cyanuric acid levels on a regular basis.

The quicker a problem is detected, the easier it will be to deal with. During the swimming season test at least twice a week.


A preventive algaecide can be added to a swimming pool when conditions are normal. Algaecides are best used in small, weekly doses. This will kill populations of algae before they grow. Too much algaecide can cause foaming or staining of your pool walls.

How To Calculate Volume Of Water In Any Swimming Pool

it’s important to know how many Liters your swimming pool holds, so you can be sure you’re adding the right amount of chemicals. it doesn’t
really matter what shape you’re swimming pool is.

Here’s a quick and simple way of estimating how much water is in it. Start by measuring the length and the width of your swimming pool by pacing it out in steps that are about one meter in length.

Lastly, measure the depth using your swimming pool pole, hold it vertically in the shallow end and mark the depth of the water and estimate how many meters it is. Then do the same again in the deep end.

Now add the two depths together and divide by two. This will give you the average depth of your swimming pool.

Ok, now just multiply the length by the width by the depth in meters then multiply that answer by 1,000, and this will give you your swimming pool volume in liters.

It might be easier to group your swimming pool into one of the 3 most common swimming pool sizes.

A small size swimming pool is up to 30,000 liters. A medium-size swimming pool is around 50,000 liters and a large-sized swimming pool is more than 50,000 liters.

Now you know what size your swimming pool is you can manage the water treatment perfectly.