very VERY VERY old water

[kluzo]

a good at least 6-7 months from the last water change. Is there any thing extra that should be done  while doing the water change?  No chemicals have been added in about 1-2 months. I will be putting in a new filter but I have not yet seen the condition of the current one. I assume it is toast.

It has been about 4-5 months the last time it was used.  

[hottubdan]

Depending on age of filter, it could be cleaned with a cleaner/degreaser.

You might want to use a pipe cleaning product like Spa Purge or Swirl Away.

[Steve]

Swirl away is good product but I'd also shock the liv'n B Jesus out of it prior to dumping or with the fresh fill before using it.

I'd also put the filter in bleach for 10-15 minutes and then rinse it off. Use your regular filter cleaner after that if indeed it's salvagable. Once you look at it, you may just decide to chuck it...