This is in response to Chemgeek's query at to my fill water being high in TA.
Just tested my tap water, which is what I top up/refill my pool with and the TA test shows TA at 100. This is pretty average isn't it?. However, whenever I have topped up my pool during the summer the TA level goes up in the pool and I lower it with Muriatic acid.

Thank you for all your help. The algae is definitely clearing and the pool is much clearer but with the CYA so high I'm always going to be battling unless I use very high dosages of chlorine. So I am now intending to half to three quarters drain the pool. We don't get enough rains here in California to make a real difference (unless you count the ones we got in 2003)

I'll let you know how I get on