Well I am undecided whether to allow it as a capital expense over a few years or not :

As I see it, these are things that wear out, as does your hose, your pump, mebranes, brushes and so on.
Just about the only thing that doesn't is your water tank, and even so, what if you disgard your 250l tank and upgrade to a 400l or larger....
Sometimes it is better to allow things as a capital expense and claim for them over a few years so as to spread the benefit.
Some of you will make a pole last donkeys years (so to speak) others won't...
Ian