Okay here's the deal, about 3 months ago I got a new cover for my hot tub. We drained, cleaned, and replaced the wet end pump at the same time. Since then my water has been very difficult to manage, The PH is off the charts and chlorine is way low, after taking several weeks to get it normal I open the cover and find a scum build up on the inside of cover! That was a week ago and now it looks like there is a mold growing on the inside of the cover.
Any Help would be great!
Thanks

You need to test more things. Calcium hardness - if low can effect sanitizer. Alkalinity - buffers pH and if low can also effect sanitizer. I would drain & refill again -it's easier than dumping a bunch of acid to get the pH down. Test the tap water to see if pH is high.
After full - 1st test and adjust calcium hardness, then alkalinity, then pH and finally add your sanitizer. If using Bromine or Chlorine Tablets I recommend testing twice weekly for tablets are very acidic.

Pete
http://www.makesmeshutter.com

Thanks, I'll drain and clean it.
I know the PH out of the tap is pretty high.

If the pH out of the tap is very high and it is city water you might want to contact your city - high pH is not a good thing.

Pete
use this advice at your own risk
http://www.makesmeshutter.com