Hello from London Ontario Canada

Welcome to TFP!

Most of the time, the problem you describe is due to insufficient chlorine. Post your normal FC and CYA levels and we can advise you better.
 
Welcome to the forum!

Also suggest adding information about your pool and related equipment in your signature. By doing this, it will automatically appear in all your posts so you do not have to re-enter it each time. [/list]
Here's how to do this: Pool School - Read This BEFORE You Post.

Not sure what kind of pool cleaner you have, but if there is a fine-mesh silt bag, I would try that. Every couple of springs or so, we get a fine film of silt caused by dust blowing in from West Texas. It's usually not visible in the air but it's noticeable when it lands in your pool. This has worked for me.