Posted by Mark Pitts on October 30, 2010 at 6:19am
Just interested in what you do in the US, its an interesting subject in the UK, where the old pool guys did it during the winter months to generate work.
I have been switching all our sand filters over to glass media . We did 6 heavy use pools in the spring and have had great results. I have opened the filters up at a few this fall and from what it looks like, the backwash cycles are cleaning better. I see less hair and junk on top of the media bed compaired to ones with sand. We are happy with the product.
Sand filtration will remove particles as small as 40 microns when the sand is new as time passes the edges of the sand wear due to the flow of water through the filter as such the particle size will increase as time passes. Generally replacing the sand every three years offers the best all around value and performance. When replacing the sand be sure to fill the tank with water first to reduce the strain on the laterals. Regarding Zeolite being crushed clearly that is a case of excessive pressure and flow rates. We as an industry really need to re-examine how we design and install filtration systems. Ramming water through a filter is not the ideal way to go as it frequently reduces filtering ability and can cause excessive wear due to the higher flow rate and pressure. It is much more efficient to use lower horse power motors and larger filters to maximize filtration and minimize costs of operation. Also when using zeolite it is suggested you cover the laterals with pea gravel before adding the zeolite, I have had old timers say the pea gravel should be used all the time even in sand filters as an aid for backwashing.
I was getting a good price on "zeobest" i used it in few filters without any problems but recently switched back to mystic white sand due to some people saying that not all zeo's are equal and some of the softer zeo's (i.e. zeobest) can ultimately get crushed from filter pressure resulting in a concrete like slab inside the filter.
My customers have there sand changed every three years (unless on Biguanide then every year). I and the most of the installers in my area put unions on TM sand filters already, and use a slurry device to remove the sand. The average sand change only takes an hour tops and there is very little risk to damaging the filter. I also recommend that when they change the sand they use zeolite to improve the filtering ability.
I'm a "never change the sand guy". Although I do think sand will loose some of it's rough edges over time that help trap debris I believe that the benefit of changing the sand isn't worth potential risk of damaging the center sand pipe when digging out the old sand. Also keep in mind that removing the port valve will usually require unions to be installed or the plumbing reworked. All things aside for the small bump in filtration I just don't think its worth it.
I have customers that want their sand changed every year because the dealer that installed the pool told them it needed to be changed every year, I also have customers that have not changed their sand in 20 years and never had a problem.
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