Tenant asking to replace sprinklers in back yard

[Varinder Kumar]

So my sprinklers are brand new its a new irrigation system actually. My tenant messaged me today if I can change the sprinklers to new ones he says because the pressure is not enough to make the heads of sprinklers pop up completely. there are about 12 sprinklers in the backyard. I told him I don't have that in my budget at the moment to do it. 

I just renewed the lease to another year of them and did not raise the rent because they are good tenants and I'm netting positive anyway. I told him he has my permission to change it him self if he likes and he can take the heads he bought when he moves out. 

He is saying the the grass is dying. There is a water hose in the backyard also for him to water if he needs. 

Any advise on best way to proceed with this without hurting anyones feelings? lol 

thanks in advance!