Pump stand

I know that you should stand the pump on something to (hopefully) keep it
out of the silt and the most common thing for this purpose seems to be
bricks. Well, I haven't got any bricks to hand but I have got a couple of
breezeblocks; are these safe to use? Are there any chemicals that could
leech out or any other reason why I shouldn't use them? Or should I just get
a couple of bricks?

Cheers,

Mogweed.
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