So I've got a Hayward S220T sand filter. It's about 10 years old, and has the original sand as far as I know (I'm not the original owner). Over the past couple years it has been leaking more and more sand. There are decent size piles of what can only be filter sand right under the return jets. It has to be dealt with at this point. I've found a few threads here on the issue, and I'm fairly sure I need a lateral assembly (SX220DA, approx $50). My dilemma is the sand. Now my water clarity is decent. My filter pressures have slowly risen over the years, up to about 12 PSI now after backwashing. This doesn't seem too alarming to me, but it got down to 10 a few years ago. The consensus around here seems to be that you rarely need to replace the sand. However, since I have to tear everything down to replace the laterals, wouldn't that make sense to do in my case? That #20 sand is $.50/lb at Walmart, so it will add $125 to the project for 250 pounds. It's not an insignificant expense, but I have a budget for it and expect it should last another 10 years. I'd like to hear some opinions. At a minimum, I'll probably need to "top it off" to account for the loss. I don't have unions on the plumbing (of course) so it's not trivial to just have a peek in there. Thanks!
EDIT: Argh, the thread title should be: replace filter sand along with laterals?
Moderator Edit - Title changed