why not x3 onto the block ! yes it will kill the suction mate ............
How about the old fashion hose pipe.
Didn't you use waterproofer?
Just to get this straight in my head. @Bones10
Were the blocks sucking fiercely when applying the scratch coat?
If so did you hose the blocks before carrying on with the scratch coat?
Did you leave the scratch coat to cure before topping?
Did you keep the scratch coat as wet as possible for the first three days during curing?
Was the scratch coat hard before topping?
Or
Did the scratch go on fine without a lot of suction but there was fierce suction when topping?