Thanks Waterbear. I was wondering about tempurature effects too. I have the pump suction to about 80% skimmers and 20% bottom drain, so it's probably getting fairly warm water off the top. When I test the water, I fill a test bottle from as far down as my arm can reach, so it's probably a bit cooler than what the skimmer picks up.

Sounds like it's all within a tolerable range. At least now, I have strips, drop test, and the aqualogic, so I'll occasionally test all three to get a general feel for where things are at.

Thanks,
Robert