Dichlor is very acidic and is probably what is pushing your pH down. Just keep an eye on it. I think you are much better off using some bleach instead of more dichlor so your CYA won't go up any further. Keep your pump running 24/7 while you are trying to clear it up. Don't be too quick to add flocs or other products. It takes time to filter out dead algae. Give it a chance.