I purchased a 25 litre bag of hydroleca for £15 and I now I'm thinking I may have the wrong stuff and should have purchased the balls instead, The pellets are irregular in shape and float. Will this make them useless for a terrarium base layer? I'm
They'll sink over time, I really wouldn't worry about it. With a heavy layer of substrate on top of them as well, they shouldn't float at all, so you should be fine.