What DPD is, is limited. Your range may only be to 5ppm for chlorine.

I THINK the "CarlD Shotglass Method" will work with DPD. You dilute the pool water with steam distilled water (avail at chain drug stores). 1 shot pool, 1 shot distilled doubles the range your read. 1 shot pool, 2 shots distilled triples it, but your accuracy gets harder and harder to maintain. DPD should also allow you to differentiate FC and CC.