Changing The Sand In A Sand Filter

Changing the sand in a sand filter

This post will cover how we change the sand in a Pentair Triton II TR-100 sand filter written by www.WCPandS.com. (Image from pentairs main site)

This is not meant to act as a complete standalone guide on how to change the sand. Wine Country Pools is not responsible for any damage occurred from use of this article. If you are not sure about working with a sand filter find a local professional to perform the work.

Getting started

It is recommended to allow the sand filter to sit off, drained of water and open for a few days to allow the sand to dry. To do this, turn off the pool system and make sure that the system will not come back on automatically. The easiest way would be to turn off the breakers for the pump.

Now open the air relief valve at the top of the filter.

Remove the top of the filter. The top will unscrew. There is a tool called a “6 inch wrench” that comes with the filter that makes this process easier. If your filter is missing this tool, you can turn lid by hand.

Remove the drain plug from the bottom of the filter by unscrewing it.

It can take 2-3 days for all of the water to drain and the sand to dry. In this example, we had less than 24 hours so it will show the process with wet sand.

Removing the sand

There is about 600lbs of sand and/or gravel in a TR100 sand filter. The old sand, once removed, will need to be moved somewhere. Find this location before starting the removal.

Looking down into the inside of the filter, you can see the “Diffuser Assembly.” This can be unscrewed.

There is a “Tube Air Relief” that passes through the top if the screen cap is pulled off. As you turn the “Diffuser Assembly,” push this tube down until it is free from the diffuser.

If the sand is dry, it can be vacuumed out with a shop vac style vacuum. Since the sand in this case was still wet, a plastic scoop was used to remove the sand.

Once the sand level is low enough, the “Piping Assembly” can be unscrewed and removed from the filter.

To keep it out of the way, I stuck the “Tube Air Relief” through the open hole that was left from removing the “Piping Assembly”.

It took about 45 minutes to remove most of the sand by scooping it out to where the “Laterals” were visible.

The “Laterals” can be soft so the dirt/gravel around them needs to be removed carefully. Your filter may have gravel (rocks) in this area instead of sand. Either way, it all should be removed.

If the sand is still wet when most of the sand/rocks are out, getting the last of it can be difficult. If you only have sand, you might be able to wash the remaining sand out with a garden hose through the bottom open drain. If not, then the filter can be freed by unscrewing the unions.

Note: These unions may be soft and can crack easily.

With the unions removed, the filter can now be moved and/or turned over to allow for the remaining sand to be washed out with a garden hose.

Once finished, place the filter back in to its original position and reattach the unions.

Reattach the drain plug to the bottom of the filter.

Refilling the filter with sand (and maybe rocks)

The Pentair TR-100 sand filter will hold 600lbs of sand or a mixture of sand and pea gravel (small rocks).

There are advantages and disadvantages to using pure sand or some gravel at the bottom and sand on top.

Refer to the table in the owner’s manual (link) on how much of each to use.

A Mixture of sand (450lb) on a bottom layer of gravel (150lb) was used in this case for its increased water flow properties.

The instructions suggest adding water to the filter first. This step was delayed because it was feared that blindly adding the gravel could damage the exiting “Laterals” if the gravel wasn’t filling all of the spaces under them.

If you are using just sand, then fill the filter halfway with water first before slowly starting to add the sand.

If using gravel, slowly start adding in your bottom layer.

Now fill the filter about half way with water.

Before the water/sand level gets too high, reinsert the “Piping Assembly.”

Now reattach the “Diffuser Assembly.” Remember to also pull the “Tube Air Relief” back though. The tube should be easier to maneuver around since the sand level is still low.

Reattach the screen cap to this tube.

The “Diffuser Assembly” was turned to the side to make adding more sand easier. As the sand level gets higher, be sure to move this Diffuser up to keep it out of the sand.

Continue adding the rest of the sand. There should be an 11 inch gap between the top of the sand and the top of the filter.

Finishing up

Reattach the top of the filter by placing it on top and screwing it down. This only needs to be hand tight.

The sand will need to be rinsed before staring the system. Move the multiport valve position on the filter to backwash.

Turn on the system to allow the new sand/gravel to be cleaned.

There isn’t a set amount of time needed to complete this step. It usually takes no more than a few minutes. The water should be a dark brown at first, then change to a lighter brown.

When finished, turn the system off, move the multiport valve back to “hi-flow,” and restart the system.

Open the top air relief valve to remove any air left in the filter and close once water starts to come out.

And it is finished.