PPI10 would be my guess as well.or even 10.
Hi jagillham where were you looking to get your sheets of foam from? Just starting up a sump system so want to get foam source without breaking the bank.Thanks everyone - will order a sheet of 30ppi and see how I get on.
For a sump you can use pieces of lavastone too, dead cheap and in a sump you should have plenty space. Pro-tip: put them in some kind of bag to facilitate rinsing them out (to get rid of to much accumulated dirt).get foam source without breaking the bank