Back Wash More Often for Low Speed?

[AMBesq]

I have a 1.5 hp Hayward Tristar pump that I run constantly on low speed. When the filter is clean, it reads 0 psi on low speed, 20 psi on high. If the psi rises to 5 on low, it barely pushes enough water through the jets to notice it on the surface of the water. Meanwhile, if I switch it to high, the PSI is about 25 and the water flow is fine.

Are you supposed to backwash DE filters earlier than normal (i.e. less than a 10 psi increase) if you use the low speed setting?

 

[jblizzle]

We recommend you backwash when the pressure goes up 20-25% of the clean pressure on high speed to maintain adequate flow. Sounds like that is exactly where you are at and see why we recommend that as the flow is greatly decreased.

Posted from my Droid with Tapatalk ... sorry if my response is short

 

[AMBesq]

Thanks for the quick reply.

 

[UnderWaterVanya]

0 psi makes it hard to find 25% rise... Let's treat it as 1% with your final result of 5% treated as 6%. This fiction is to discuss the math.

1% rising to 6% is a 500% increase.
20% rising to 25% is a 25% increase.

I would have thought that you should backwash when your low speed (which I assume is your primary use) pressure reached 1-2 PSI over your starting point to avoid the reduction in flow.

I wonder if there is a downside to trying it both ways.