try this get a peice of pvc a cap and way to attach it to the pump- now take and drill, in a vice, the pattern of spray you 'd like using a 1 mm or ? drill bit, heated metal poker whatever. I would bevel the holes with a knife just slightly. it will also shape the spray, hook it up and test it until you get something you like then see how long it takes to plug up. 

make your own spay head then when it gets plugged make a new one. this is doable and if you have access to metal working equip skip the pvc and go with brass. easy to work with.

also they make a line cleaner that works great for these systems. Drip Clean? going to incorporate it my next indoor season myself. suppose to work really well at keeping the lines clear of organics. which has just started to get me a headache.