Need to replace sand!

mwwhited

Member
Mar 10, 2015
9
Johnstown, Ohio
After just pulling a sand filter and replacing it with a cartridge I am going to call B.S. on never having to replace the sand. The filter was a mess, cake all caked up and the sand partials were like tiny rounded off beads. I tried several times to clean the sand filter by soaking it in a cleaning agent to break down the biomatter then backwash (so much wasted water). Also had one heck of a time trying to keep the water crystal clear. The new cartridge is amazing and no more backwashing/dumping hundreds of gallons of chlorinated water.
 

jblizzle

Mod Squad
TFP Expert
LifeTime Supporter
May 19, 2010
43,238
Tucson, AZ
Re: Switching to SWG

After just pulling a sand filter and replacing it with a cartridge I am going to call B.S. on never having to replace the sand. The filter was a mess, cake all caked up and the sand partials were like tiny rounded off beads. I tried several times to clean the sand filter by soaking it in a cleaning agent to break down the biomatter then backwash (so much wasted water). Also had one heck of a time trying to keep the water crystal clear. The new cartridge is amazing and no more backwashing/dumping hundreds of gallons of chlorinated water.
Well that would put you in the minority. There are macroscopic photos on the forum showing no difference in the sand after years of use. The only time the sand is even moving in the filter is during a backwash. Now if you used some of the pool store's magic potions incorrectly, that could certainly gum up the sand and require replacement.
 

JasonLion

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May 7, 2007
37,879
Silver Spring, MD
We don't recommend using sand cleaner. There are instructions on cleaning out a sand filter here.

Backwashing does indeed waste water. That is the tradeoff with a sand filter, easy to use, but you have to dump water.

The one time you do need to replace sand is when you get calcium scaling inside the filter. That causes the sand to clump up into clumps that can't be easily broken up. When that happens you do need to replace the sand. Of course if you keep your chemistry balanced correctly, that can't happen.
 

mwwhited

Member
Mar 10, 2015
9
Johnstown, Ohio
They chemistry was perfect on the pool and it would still get cloudy at the drop of a hat. (it's an indoor pool so there isn't even much biomatter falling in.) It might have just been poorly maintained before I bought the house but the sand was a mess. Either way I don't like the wasting water that came from backwashing/rinsing the sand and the cartridges are much easy to deal with and use much less water.
 

duraleigh

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In The Industry
Apr 1, 2007
34,429
Sebring, Florida
The most important thing is what works best for you and helps make it easier for you to maintain your pool.
I quite agree.....but it is probably not prudent to "call BS" on a method and product that has been successful for thousands upon thousands of users.

I have personally never changed the sand. I installed it new 9-10 years ago and when it is cleaned in the Spring, it essentially looks new again and I would be quite surprised if it is EVER replaced.
 

Kiss4aFrog

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TFP Guide
May 22, 2013
2,738
Hudson, WI
The previous owner used to flock and change sand every few years but I've had the same sand for 7+ years and last year was the first time I took it apart and deep cleaned it. How to - - > http://www.troublefreepool.com/threads/73192-Deep-Cleaning-a-Sand-Filter

That was an eye opener on what all floated out of there :pukel:

I've had no problems or complaints with my filter but that's the nice thing about having options. If you don't like sand go with a DE or Cartridge.
 

chem geek

TFP Expert
LifeTime Supporter
Mar 28, 2007
12,083
San Rafael, CA USA
The issue is NOT that the sand got old or worn which is why we say it need not be replaced. What you are describing isn't a problem with the sand. It's a problem with getting biofilms in the sand and that causes it to cake and have channels. The water chemistry in the pool probably had the FC/CYA ratio get too low for too long and allowed bacteria to grow in the sand filter. For biofilm in sand filters, one can use Ahh-Some for pool/tub filters, though just as with algae it's far better to prevent the problem from occurring in the first place.
 

applgrl

Well-known member
May 22, 2011
49
I wonder what would have happened if you did put new sand in, and then ran the system. Not that I recommend it--smelly messy, job! We have (properly? I think!) maintained a sand filter for 40+ years. The sand we replaced around the 30 yr mark did not significantly change the pool function in any way. We had replumbed the pool and just thought maybe we should. Both before and after we backwash about 150-200 gallons once or twice a week. The only chemicals I've routinely used are chlorine, calcium, baking soda, and CYA. I haven't had much success trying aluminum based flocculants and filter cleaners. I've not experimented with adding DE to the filter. In your case, you had to do something, either change the sand or upgrade the filter.

A sand filter probably doesn't have the clarity of more modern systems--storms and high bather load will overwhelm it pretty quickly. If the tank wasn't sized properly, or if previous owners threw chemical willy-nilly into the skimmer instead of into the pool (calcium!) then it would explain your issues. I might also mention that my pool stays much clearer in colder weather than in warm. Your indoor pool likely provides a better temperature for algae/bacterial growth, 24/7, and the sand filter wasn't able to keep up. Your cartridge filter sounds great: if we didn't have water turbidity issues, plus a seasonal outdoor pool, I would be inspired to change over.

The strength of the sand filter is that it is simple, cheap, and will last a long, long time. The weakness is that it requires vigilant attention to FC, tank pressure, and it can easily be overwhelmed. The takeaway from this thread is that sand DOES need to be changed when you can visually see a problem in the tank.
 

Kiss4aFrog

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May 22, 2013
2,738
Hudson, WI
I think everyone agrees if you see a problem with the sand it's time to replace it you just don't need to do it as a routine maintenance item as is often recommended by pool stores and pool service companies.