Shilala Beads vs. Heartfelt

I like Shilala beads, but I use Heartfelt in my 120 quart cooler, mostly due to cost. I have 70% Heartfelt beads, but my cooler never goes abov 67%, even after they have been recharged. Holds in the 66-67% range, and I only have to recharge them about every 4-5 months in my climate.