How much sand is too much?

[Smykowski]

I've got a Hayward S180T sand filter (150lbs according to the manual) and a Hayward PowerFlo Matrix 1.5HP pump. I've never touched the sand except for deep cleaning with a hose. I'm wondering if I've lost some over the last 2 years due to backwashing and need to add some more. Problem is, there's no fill line. I'd like to avoid taking it all out just to weigh it and put it back in.

If I top it off, what's the risk that I overfill the sand? How would I know I put too much in? Can you put too much in?

 

[JasonLion]

Sand filters will lose a little sand over time, but usually the quantity lost is so small that it doesn't make any difference.

You can put too much in. If it is only a bit too much it will simply backwash out over the next several months. If you put in way too much, say twice as much are required, the filter will probably break, but that would take some doing.