Typical backwashing frequency with 2 sand filter size options for my pool

[kevreh]

I have a ~24k gal in ground pool with (currently) a DE filter. Switching to sand for lower maintanence and less backwashing. Getting a 24" (hayward Pro Series) will be just about right, and 27" slightly larger. I know larger is better, but from a practical standpoint how much more backwashing will I need to do if I go with a 24"?

 

[jblizzle]

Hard to say, depends on the debris your pool gets.

The 27 has about 25% more area, so perhaps it would require backwash 25% less often

 

[JoyfulNoise]

I'm not sure a sand filter will require less backwashing or any less maintenance, all filters require some level of annual or semi-annual maintenance...I don't ever backwash my DE filter, just tear it down twice per year. I have an oversized DE filter though - QuadDE100 (100 sq ft) for a 15k gallon pool. If you want to get rid of DE, I would suggest you go with an oversized cartridge filter as the fine particle filtration performance will be better than a sand filter. Cartridge filters also don't use backwashing...they simply get loaded up and you open them up and clean the filters as needed. In many areas where water usage is a concern, cartridge filters use the least amount of water.

Backwashing recommendations here are the same for all filter types - you backwash when your filter pressure has increased 25% over clean pressure. So, if your filter clean pressure is 10psi, you backwash when it hits 12.5psi.

 

[kevreh]

WOW, 100sf for a 15k pool! Your probably pretty a-typical in terms of backwash frequency with a filter that size. My current DE filter is only 36sf. Guess thats why it clogs so quickly. Is there a performance rule of thumb comparing DE filter size to Sand?

Cartridge is appealing, but quite a bit more money, and taking the grids out sounds more labor intensive. Lot of folks here seem happy with sand.

Hard to say, depends on the debris your pool gets.

The 27 has about 25% more area, so perhaps it would require backwash 25% less often

Hmmm. That's one way of thinking about it. I'm getting rid of my DE filter because it requires backwashing every few weeks and I look forward to not dealing with the powder (amongst other reasons). I would hate to go to sand only to find I still need to backwash often, even though its easier.

Also, if I use a 2 speed pump on lower power, but on longer, does this change the size filter to buy?

 

[JoyfulNoise]

WOW, 100sf for a 15k pool! Your probably pretty a-typical in terms of backwash frequency with a filter that size. My current DE filter is only 36sf. Guess thats why it clogs so quickly. Is there a performance rule of thumb comparing DE filter size to Sand?

Cartridge is appealing, but quite a bit more money, and taking the grids out sounds more labor intensive. Lot of folks here seem happy with sand.

Yeah, I oversized specifically to avoid issues like the ones you are having. I actually missed my semi-annual tear down back in September and recently completed a tear down in early April - my filter went an entire year without backwashing and I could only barely start to see the performance slow down. Filter sizing is one of those things where bigger is almost always better! Many people here in our build threads will oversize their filters, it just makes living with a filter that much easier. An oversized cartridge filter (example, Pentair Clean & Clear 520) would probably go an entire swim season before it ever needed to be cleaned.

Anyway, you are right, many people here like sand filters. My personal preference is better filtration performance so I went with DE and oversized it since that makes the maintenance a whole lot easier.