Hi, If you happen to have the Rainbird 1800 series pop-up heads, then the item you need is called ''RainBird Replacement Cover/Seal Assembly for 1800 Models'' and the Rainbird part number is 116901. You can buy these on-line from Rainbird for $2.30 each, or you can find them at many other on-line retailers. I have not had any luck finding them from Lowes or Home Depot either in their stores or on-line. Regards, Andy in Friendswood (Houston, Texas) Lawnboy_10525 Reference: http://store.rainbird.com/shopexd.asp?id=933 Here is a link that might be useful: Sample on-line store Evergreen Sprinklers

The material the sprinkler is made of doesn't matter. You need a sprinkler that uses a smaller amount of water and that shoots far enough to cover your area. It sounds like a single stream rotor is what you want. All home improvement stores have these.

The system was designed with full overlap. meaning each sprinkler shoots all the way to the next sprinkler. To tested my theory I took one of the sprinklers off and put on a pressure gauge. At 9 remaining sprinklers running i was getting about 20psi when I turned few off and had only 5 running i it to about 35-40psi and at that point I could clearly see an increase in coverage. Looking at the heads chart my 12ft head shoots about 10ft radius at 20psi. it also uses 2.1gpm I have 6 360 heads and 4 180. looking at the same chart at 20psi they use about 16.8gpm and I have 17gpm. so the amount of water should be sufficient.

I have two systems - the rainmachine (8) at my rental and the orbit bhyve (I think it's 12) at my house. Because I've been dealing with reseeding off and on for a couple of years (note, fix any broken sprinkler heads first), I've had my rental/RainMachine on more me-controlled rather than weather based. Remote access is awesome, I definitely have to say, since that's allowed me to tweak the schedule based on the rain predictions (since seeding requires more than in maintenance state, and I guess a ding would be that there's no "seeding" choice for the plant type, but doubt anyone has that). I chose the rainmachine about 2 years ago based on the fact that I wanted a controller that didn't rely on the company being an ongoing entity - one of these companies WILL eventually go belly up. It's been working great for me in this scenario, though I do currently have an issue with remote access on it, but I think this has more to do with my tenant's internet connection and I haven't had the time to troubleshoot it with the holidays keeping me busy. I literally have not had to open the weatherproof box I store it in for the last two years, so much so that I've forgotten how to use the buttons on the device (of which there are really none, being the 8 version). For the B-Hyve, I've had it for about a year and a half, and have it using SmartWatering (weather based). I did purchase a sensor for it at one time, as that was required in order to get the Water District rebate (so this one essentially cost me $0). I will give it much credit because all my plants and grass are still alive relying on it to make the watering decisions. I have definitely seen it skip in periods of rain (we are in Northern Cal, in a perpetual drought, but saw record breaking rain last season). The app can be a bit quirky - like it will have watered that morning, but the rest of the parts of the app need to be caught up on this info like saying tomorrow it will smart water, but wont end up actually watering again tomorrow because it does eventually catch up. It's gained my trust (to water as well as not water), so I've been able to look past that. I am currently having an issue where my front yard zones are not turning on, neither on the app or directly at the controller, but I'm guessing that this is also something unrelated to the system (like I probably need to check the wires) and again, havent had time to troubleshoot it (not urgent since it's almost winter), I will say that the b-hyve having knobs is nice, as I know the gardeners could probably test the system if need be, while with the rainmachine - the tenant's gardeners doubtfully have loaded the app on their smartphones! And I guess the b-hyve gets points because it comes in an outdoor enclosure (had to make my own for the rainmachine, since I needed it to be outside of the tenant's dwelling). And since it's orbit, you know they are not going anywhere anytime soon. A ding with B-hyve is that I don't find much online/in forums about it for troubleshooting - not sure why orbit wouldnt sponsor that so that people can get the wisdom of the crowd. I say with either of these two, you probably cant go wrong. The rainmachine is pretty, so if you plan to have this in your house, I'd chose that. I guess I would say I like the graphs of the rainmachine app better, but that may be unimportant once you just have it at set-it-and-forget-it state.