We shifted from a fixed 3 a.m. backwash to differential-pressure triggered cycles and staggered the four sand filters, which cut water loss about 20% and shaved roughly 40 minutes off opening prep. For those running similar setups, what DP threshold (we’re at +7 psi) and minimum run-time lockouts are you using to balance clarity and uptime?
We run +5 psi, 30‑min lockout; at ‘+7 psi’, try 45‑min — any NTU rise?
At +7 psi, the biggest win for us was adding a 20‑hour ‘max-interval’ backwash to catch low‑load days, with a 60‑min lockout; it flattened NTU blips without costing uptime, like giving the filters a set bedtime. What’s your NTU right before opening?
@davidson_jay nice call on the max-interval; we also added a DP ‘rate-of-rise’ trigger — if ΔP climbs >0.5 psi per 10 min for about 30 min, it backwashes even before +7, and a 25 s rinse keeps NTU spikes down (like a quick espresso rinse). Any chance you’re trending DP slope in the controller? That tweak smoothed our NTU trace while keeping availability.
Nice on the ‘shaved roughly 40 minutes.’ At +7, the turbidity blip after backwash drives me nuts, so we send effluent to waste until it’s <0.3 NTU or about two minutes, then ramp flow back over five; it flattened the spike without hurting uptime. Do you have inline NTU, or only grab samples?
We’ve seen water temp skew DP enough that a flat +7 psi is a fibber, so we tweak the trigger by about ±1 psi with temperature (lower when warm, higher when cold) and it trimmed false trips without dinging clarity. If you’re on a VFD, watching % flow at a fixed Hz has been a good early fouling tell — about a 5% drop prompts us to prep a backwash window. Curious whether @davidson_jay has blended temp‑comp into their ‘rate‑of‑rise’ logic.
I’d keep your “+7 psi” but add an 8-minute dwell at/above threshold so bather surges don’t trigger it; that cut our nuisance cycles about 30% on four sand filters. We lock out each filter for 70 minutes after a backwash and clarity’s held steady during opening prep — are you ramping VFDs back up or snapping to full flow?