Hi Tim;

It's hard to judge whether your pool's chlorine loss is above normal or not, till you have been able to hold things stable for a while. In general, chlorine loss seems dependent on the CYA/CL ratio + pH more than on absolute chlorine level. BUT, chlorine demand can be fast or slow, depending on what the source of the demand is. For example some components of urine are oxidized slowly, and will continue to exert chlorine demand for quite some time after the 'incident'.

In fighting algae, one very important factor to keep in mind is that it's not over till AFTER you think it's over. In other words, keep brushing and keep the chlorine high for several days AFTER there's no detectible algae. Also getting in the pool and feeling for 'slimy' spots can be a very effective 'early warning' method in vinyl pools.

I'll get back to you later today, with some more info.