dafletcha,

Don't forget that part of the reason for having higher CYA with higher chlorine levels is to have enough in "reserve" so you don't go below the minimums at any time during the day. If your pool is exposed to sunlight, then it may lose around half of it's total chlorine in a day assuming you have at least 30 ppm of CYA (it will lose even more with less CYA). If you have a pool cover, then you can probably have low CYA and low chlorine levels, but without a cover and with exposure to sunlight, you might not be able to do it.

See what your chlorine loss is during the day and specifically between the times you pour more chlorine into your pool. If you think you can keep a minimum level, then fine, but if not, then it's better to play it safe with higher CYA and higher chlorine. That's why Ben's chart doesn't "roll off" to very low FC at low CYA because it's really hard to maintain very low FC in outdoor pools exposed to sunlight.

Richard