I also have an Aqualogic and have had exactly the opposite results. I had a leak in my pool so my CYA level was dropping and I found that as soon as my CYA dropped to about 50 I had to crank the output on my cell up to mantain the 3 ppm FC in my pool and the 4-5 ppm FC in my spa. This happened to me twice so it was a repeated effect. Once I bumped the CYA up to about 70-80 ppm my FC levels rose and I had to back off on the output. I currently run my pool at 8% and my spa at 4%. When the CYA levels were lower I has the pool at 20% and the spa at 8%.