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Posted by E-Z Test Pool Supplies on May 17 2017

Sand Filters 101 – How Important is Sand Quality? – Changing Your Filter’s Sand (Part 2 of 3)

In our last blog we discussed the reasons for changing filter sand as well as the need for using a quality brand of silica sand – we recommend Mystic White II™ silica sand from US Silica. In this blog and the one to follow, I have chosen to focus on the proper method for changing the sand in the filter tank. 

sand for pool filter, filter sand 50lb bagAlthough the general idea is “old sand out, new sand in”, there is much more to the process than you might think. For this reason I have chosen to divide up the process into 2 parts.

Before we begin, it is worth noting that you need to use the correct amount of sand that your filter requires. Too much sand and your filter will likely not run correctly or may break when reassembling. Too little sand and you will have cloudy water no matter how much your filter runs. For this reason check your filter manufacturer’s specs. Typically filters hold sand in 50 lb. increments, so you can safely expect filters to range from 100, 150, 200, 250 lbs., etc. Also, a project such as this is worth doing correctly and thoroughly, so plan on having all of the items on hand BEFORE you start!

CHECKLIST OF ITEMS YOU MAY WANT TO HAVE BEFOREHAND

  • CORRECT AMOUNT OF SILICA SAND FOR YOUR FILTER
  • NEW O-RING BETWEEN THE MULTIPORT AND THE TANK
  • TEFLON TAPE FOR THREADED FITTINGS
  • UNION FITTINGS
  • SILICONE LUBE (DO NOT use petroleum based lube!!)
  • ADDITIONAL O-RINGS AS NEEDED (This is a good time to change while apart)

First and foremost, be sure that the pump is off. You may even want to cut power to the pump to prevent mishaps. If working on an above ground pool or any filter that is lower than the pool water level, you will need to block the flow of water out of the pool. This can be done with threaded plugs (1 ½” standard plumbing thread). Next, remove the filter drain cap to allow the filter to empty out. Be sure to put the cap back on BEFORE you lose it. The filter cannot run without it!

Sand Filter - side mount

TYPICAL SIDE MOUNT MULTIPORT SAND FILTER WITH 2-PIECE TANK

Sand Filter - top mount

TYPICAL TOP MULTIPORT
SAND FILTER

Then depending upon where the multiport valve (the mechanism that allows you to change between filter, backwash, rinse, etc.) is you’ll need to open the tank. If it is on top, you need to disconnect the plumbing or hoses connected to the multiport.

For pools where PVC pipe is used and there are no unions, you will need to cut the pipe with a saw. This is actually a good opportunity to install easy connect/disconnect unions for future ease. A professional pool store – like E-Z Test Pool Supplies J! – will have these unions in stock. After disconnecting all necessary plumbing attachments, you may unscrew the fitting that holds the multiport to the tank. Take care when removing this by slowly and gently twisting and pulling the valve upwards to avoid breaking the internal components of the filter. If you have the multiport valve on the side of the filter, you will likely have a 2-piece tank and can unbolt and remove the top half of the filter, exposing the sand bed. On either type of filter, be sure to cover the open portion of the stand pipe going into the filter with tape to prevent sand from getting inside the pipe – for some filters an upside down Dixie cup works well to cover. Remember, any sand that gets into here will only blow back into the pool once you’re back up and running.

Now it’s time to get the old sand out of the filter. Although there may be more than one way to accomplish this, here is a short list of DO’s & DON’TS:

DODON’T
USE A SHOP VAC IF ACCESS TO THE SAND IS DIFFICULT.USE A PAPER OR PLASTIC CUP TO EMPTYTIP THE TANK UPSIDE DOWN TO EMPTY
– a good way to break internal partsUSE A GARDEN SPADE
– another way to break pieces insideATTEMPT TO MOVE THE STAND PIPE TO THE SIDE OR UPRWARD UNTIL FULLY UNCOVERED FROM THE SAND

Once your tank is largely empty of sand you’ll need to remove the stand pipe and lateral assembly. For some models the laterals (these look like spokes on a wagon wheel) these will rotate up 90° to a vertical position. Other types of laterals will unscrew from the base of the stand pipe. Be sure that unless you are absolutely sure which type you have, be very careful in trying to turn these so as to remove the assembly. Once these laterals are out of the way, next remove the complete assembly from the tank. At this point inspect these pieces carefully for cracks or damage, as any unwanted openings will allow sand from inside the tank to pass directly into the pool. The time to replace defective or even questionable parts is NOW! It is at this point that the tank may be thoroughly rinsed with water to remove the rest of the remaining sand.

In our next blog we’ll pick up from here giving you tips on how to get it all together!…the filter that is. Sorry, I’m not a life coach!

Anyway, until next time, keep swimming!