Is 1 Backwash Sometimes Not Enough?

NullQwerty

LifeTime Supporter
Apr 23, 2008
340
#1
Hey folks,

I'm new to Sand Filters. Just got a new 350 lb one, which has been in service 1 week cleaning a very dirty pool. The first time I turned it on the PSI was around 9, give or take 1. The first couple of times I backwashed, it brought the pressure back down to 10 psi. But now when I backwash, it only drops to 12 psi when it's done. My procedure has been backwash for 2 minutes, then rinse for 30 seconds. Should I repeat the procedure if it doesn't bring it down to 10?

Thanks
 

scooperhsd

Well-known member
May 10, 2009
395
Youngsville NC
#2
I backwash mine until the water in the sightglass is clear and has most of the black particles out of it, then rinse (30 sec - 1 minute), then do another 1-2 minute wash, followed by another rinse, then back to normal filter mode. Usually I don't do the second wash / rinse and let it go at once if it didn't take very long to get clear. But I really use the sightglass for Determining when to quit washing, and not time per se.
 

Txmat

LifeTime Supporter
Jun 18, 2010
424
San Antonio
#3
I use time. 1 min backwash, turn pump off for 1 min, repeat 2 more times, rinse for 30 seconds, pump off for 30 seconds, then back to filter.
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
#4
I also use the sight glass, I backwash until it is totally clear. Then rinse until clear. Using time may not always get your filter clean, or in some cases will be overkill IMO.
 

X-PertPool

TFP Expert
In The Industry
Jun 12, 2009
1,385
Exeter, PA
#5
I believe back washing multiple times will help loosen up stubborn or heavy debris from the sanded. I think it's mostly the jostling of the water inside the tank when moving from backwash to rinse over and over that can break something stubborn free. I could be totally wrong just my theory
 

X-PertPool

TFP Expert
In The Industry
Jun 12, 2009
1,385
Exeter, PA
#7
topher said:
I wish I had a rinse function :( my old filter did. but my new -crappy - used one I got for 25 bux doesn't... will be getting a new one this winder. (i hope)

not that big of a deal, rinse is just filter to waste
 

NullQwerty

LifeTime Supporter
Apr 23, 2008
340
#9
So I backwashed a second time. So that's a total of 4 minutes plus 1 minute of rinsing. Remained at 12 PSI. Guess 12 PSI is my new base point. Maybe 10 was just because it was brand new sand or something.
 

linen

TFP Expert
LifeTime Supporter
Jul 30, 2010
8,649
Twin Cities, MN
#10
Only other thing I can think of that the change might be due to is less resistance to flow in your supply line, or more resistance to flow in your return line now.