How To Winterize A Sand Filter
Winterizing a sand filter for your swimming pool is an important step in the closing and winterizing process for your pool, and certainly one where if you do it wrong you are very likely to cause damage to your equipment. If you were to fail to remove all of the water from your sand filter or filter head then you could definitely expect to see permanent damage in the spring (if you live in a climate that gets freezing temperatures in the winter).
Your filter is especially prone to damage from freezing water, and once a filter cracks there is no repair that can be made due to the dynamic movement of a pressure vessel and the danger associated with makeshift repairs. If you freeze your filter and crack it you will be shopping for a new pool filter in the spring.
Fortunately for pool owners who are looking to close and winterize their own pool winterizing a sand filter is a pretty quick and easy process...it is just unforgiving if you forget to do one of these quick and easy steps! In short, you have to get all of the water out of everywhere within the filter including the filter head. You then need to leave the filter head in a position which will leave all ports open. None of these steps takes any particular skill or very much time but you need to make sure that you do them all. But wait - you are not ready to drain and winterize your sand filter just yet!
Before you drain and close your filter for the year you need to make sure that you have your pool water clean and fully balanced. When you close your pool you should definitely try to get the chemistry balanced as well as you can along with having the water look perfectly clear with no debris floating or on the bottom of the pool. This is how you increase your chances of opening your pool to beautiful (still clear) water next spring. If you want to learn more about this then you can read this article about how to make sure your pool is clear in the spring. If your pool is clean and clear then the last thing to do right before your winterize your sand filter is to give the filter one last backwash of the year, usually about twice as long as you would normally perform this procedure for. If you have a "rinse" setting on your multiport valve then following the backwash do a 60 second rinse to help clear any debris which might be within the filter head itself.
4 Steps To Winterizing A Sand Filter
1) Set the filter to "recirculate" or "whirlpool" if you have these settings. This bypasses the filter tank and only sends the water through the filter head itself. This is the setting you should be on when you use your blower to blow through the filter head. The actual process you use for this will include blowing through the rest of your equipment, pump and heater, but for this example we are just looking at winterizing the filter. So you would blow from the pump through the pipes which pass through the filter head and continue on to the heater. Blow until you hear no more water (or see no more water if you have the plumbing system open - each pool is different).
2) Without changing the blower or filter head settings simply turn off the blower and then remove the filter pressure gauge (careful, these break very easy) as well as the backwash sight glass. Store these items in the strainer basket from your pool pump so that they never leave the equipment area and end up lost. If you have a bleeder valve or air vent valve on your sand filter you should open this as well. Now with all of these extra ports open you can turn on the blower again which will cause some mist to blow out of the ports on your filter.
3) Turn off the blower and change the filter head setting to "winter". If you do not have a winter setting option then simply push down on the filter handle like you are going to change settings, but leave it propped up on the edge - do not progress all the way to the next filter setting. Leaving the dial valve up on the edge leaves all ports open which is the same setting that "winter" is for newer sand filters. With the filter head in winter setting or at least all ports open, give the blower one last shot to make sure there is no residual moisture left in the valve.
4) Now that you have removed all of the peripheral items installed in the filter head, you have blown out all of the water and you have set the filter head into the all ports open position you can now look at draining the tank itself. You could in theory do this earlier in the process but then you are going to be standing in a puddle of water for the remainder of the closing process. Ideally the last step of winterizing a sand filter is to remove the plug on the bottom of the filter tank. Store this in the pump strainer basket as well. Be very careful to not lose any small gaskets that may be part of your filter drain plug assembly. It will take your filter anywhere from a few hours to a few days to fully drain so you can just leave it to drain once you have removed the plug from the bottom of the tank.
These are all the steps involved with draining, blowing out and winterizing a pool sand filter. A very important tip to remember is that you are working with a lot of delicate and plastic components. This is not like pulling wrenches on an old car. You need to be careful and work with finesse, not brute strength, when working on pool equipment. Components like the pressure gauge should be removed with a wrench from the base, not by grabbing the gauge with your hand and turning it that way. Similarly items like the tank drain plug will likely have a spot for using a wrench to help you remove it.
Using the right tool for the job when winterizing a sand filter is very important. Tools like channel locks or vice grips leave gashes on the plastic. If you use an adjustable wrench be very careful to size it as accurately as you can before you lean into it. Plastic is unforgiving for stripping and rounding nuts far more so than any metal hardware. Take your time winterizing your filter. If you rush or get frustrated with a tight connection you could easily cause unnecessary damage to it.
How to open your pool to clear water in the spring
Common mistakes people make when closing a pool
Should I drain my pool for the winter?
Why does my pool lose water in the winter?
How to winterize a pool heater
8 Part pool winterizing series
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