As John has pointed out, you most probably don't have a problem with your filter - you have a problem with your chemicals. Your sand is actually millions of years old and having been in your filter for a couple of years more has not damaged it. Don't let anyone "sell" you a sand exchange. Sand in filters almost never needs changing.
From your comment "I brought in a sample and all tests were comfortably within range or slightly on the high side (Chlorine)" I will deduce that you do not have your own test kit. What the pool stores say is "within range" and what folks here follow are usually two different things.
We want you to learn to take control of your pool and it's testing. To do so you need to arm yourself with the knowledge and tools necessary to care for your pool.
The knowledge is condensed in the
Pool School link at the top of every page. It is a great community here, but we do ask that you read and try to understand the information being taught. Questions are always welcome and folks will try to direct you and teach you the methods.
The tools are not limited to the brushes, vacuum hoses and other stuff you use around the pool, but include the most important item - one of the
recommended test kits. You can buy a kit at a pool store, but again the pool store kits generally won't cut it. To effectively practice the TFPC methods, the FAS/DPD chlorine test is essential. All these kits contain that test while very few other kits do. Think of it this way, do you see a doctor blindly prescribing drugs without seeing the patient or having tests run? Here at TFP we are going to ask for photos so we can see the condition of the water and are going to ask for a full set of test results.
Additionally, it would help us if you would add the following information to your signature
- The size of your pool in gallons
- If your pool is an AG (above ground) or IG (in ground)
- If it's IG, tell us if it's vinyl, plaster/pebble, or fiberglass
- The type of filter you have (sand, DE, cartridge) and, if you know, the brand and model of the filter.
- If you know, please tell us the brand and model of the pump, and mention if is it a two speed or variable speed pump.
- Date of pool build/install, particularly important if less then a year old.
- What kind/model of water test kit you are using
- Other significant accessories or options, such as a spa , SWG, or cleaner