Rarely need to backwash sand filter?

channing321

Member
May 23, 2017
11
Mesa, AZ
Hi all,

This website and the pool maintenance guide has been an excellent source of information for me and my pool is truly trouble free for the first time (3rd year of owning this home and pool). I thought it would be annoying adding liquid chlorine every night but it has quickly become second nature and I can test the water and add the chlorine in just a few minutes, but I digress.

Since I completed my SLAM around May 15 of this year, I have maintained the appropriate chlorine level related to my CYA level and have NOT had to backwash the sand filter since then. The pressure on the sand filter hasn't even really gone up from the clean level, maybe 1psi. I only have to run the filter for 4 hours every night from about 8pm to midnight which is also when I add my chemicals. In the past, I've run the filter for 12 hours a day (pool store advice) and backwashed every 1-2 weeks in past summers and once a month in the winter months. I also battled algae all summer long the past 2 years.

Is this normal to not be needing to backwash very often? I'm stunned that I haven't needed to backwash for 1.5 months now, and that the filter only needs to run for 4 hours. I'm ecstatic with the overall reduced level of maintenance as my pool water looks great and most importantly I have not battled algae at all! I just wanted to make sure I'm not missing something.

EDIT: Figured I'd add my last full test results as an FYI

FC 5.5 (add enough chlorine every night to get this back to 10ppm)
CC 0.5
CYA 70
pH 7.6 (slowly drifts up and when it's at 7.8 for a few days I add enough muriatic acid to lower to 7.6 again)
TA 100
CH 575
Salt appx 1500 (test strip result)
 

JoyfulNoise

TFP Expert
Platinum Supporter
May 23, 2015
15,864
Tucson, AZ
You have a big sand filter on a small’ish pool ... not surprising you don’t need to backwash because you have no algae clogging it up.

In the case where you don’t need to backwash frequently, the suggestion would be to deep clean the sand filter once or twice per year and not bother with backwashing. You’re in Arizona so it's really a crime installing a sand filter on a pool as backwashing consumes lots of water and water is super-expensive here (unless you have a well). A better filter choice in this climate is an oversized cartridge filter to avoid backwashing all together. Sure, cleaning a cart filter is a labor intensive task but if you only need to do it once a year, it’s not a big deal.

Also, consider retrofitting your current pressure gauge with a liquid filled high precision one (0.5 psi increments). It’ll give you a much better feel for pressure rise.
 

channing321

Member
May 23, 2017
11
Mesa, AZ
Just trying to learn here— why do you get you fc up to 10. According to the chart for a salt pool shouldn’t it be 5-6 ?
I don't have a salt water generator. I manually add liquid chlorine every night. My wife prefers the feel when I add a little salt to the water and that's why I have a salt level to list. (y)
 

channing321

Member
May 23, 2017
11
Mesa, AZ
You have a big sand filter on a small’ish pool ... not surprising you don’t need to backwash because you have no algae clogging it up.

In the case where you don’t need to backwash frequently, the suggestion would be to deep clean the sand filter once or twice per year and not bother with backwashing. You’re in Arizona so it's really a crime installing a sand filter on a pool as backwashing consumes lots of water and water is super-expensive here (unless you have a well). A better filter choice in this climate is an oversized cartridge filter to avoid backwashing all together. Sure, cleaning a cart filter is a labor intensive task but if you only need to do it once a year, it’s not a big deal.

Also, consider retrofitting your current pressure gauge with a liquid filled high precision one (0.5 psi increments). It’ll give you a much better feel for pressure rise.
Good to know that I'm not missing anything. I think I've just been told so many wrong things in the past that I assumed backwashing would still be a routine maintenance item, even with maintaining correct chemical levels. And thanks for the advice on the pressure gauge. Any recommendations as to a good one to buy or as long as it's "liquid filled high precision" it would be fine?
 

mknauss

Mod Squad
TFP Expert
Bronze Supporter
May 3, 2014
22,404
Laughlin, NV
Any recommendations as to a good one to buy or as long as it's "liquid filled high precision" it would be fine?
 
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channing321

Member
May 23, 2017
11
Mesa, AZ
Nice! Thanks so much!