I think carino means 'hoophouse.' And yes, painting with latex paint is a good idea. The paint must be latex or acrylic. PVC releases a chemical that melts the plastic over time. The paint also shades the pipe from the sun, which will make it last longer.

For that large of an area I would strongly advise trying to get a larger source of water. Meaning a larger meter. Call your local water company and see what is required to get a 1" to 1 1/2" meter line installed for irrigation use. Not sure about your area but here in South Fla a irrigation meter does not pay sewer charges for the water use. This amounts to about 1/2 of the bill. With a larger meter you would also have less zones because your flow would be better. Lehua's 80% number is what I would have advised 10-15 years ago but in the last 10 years and even more so in recent years our local water companies have reduced our water pressure nearly 10 PSI. We are still in a very good PSI range BUT systems designed 20-30 years ago show problems with these changes. Shoot for even less IMO than the 80%....65-70% would be safer. Saying that it is even more important IMO to get a larger meter with a higher flow. Something nearly always left out in these forum questions is what pressure you have while water is being used. Having 55 PSI really tells us very little. Having 11 GPM tells us something but still lacks the real info we need. We really need to know how much PSI you have when using X amount of water. This isn't the easiest thing for a homeowner to find out but a close enough measure can be made. Place your PSI gauge on a water outlet on your source. Then discharge water. When your gauge is in the 27-38 PSI range check your meter to see how much water your using per min. This is a much better number to tell us how many heads (or more important how much water per min) you can run per zone. Good luck, Tom

If it's a large tree, it should have stakes with tape out about 5 feet from the trunk to protect the roots. If it's an oak, they'll probably kill it with the equipment anyway.

I based my length of copper on a desire to match a 3 ton AC system (36,000 BTU/hr) with the copper water to water coefficient of heat transfer (60 - 80 on the chart, so I used 70) and a 30 degree heat difference. That heat differential was based on the fact that my pond is spring fed (I'm using a rough calc of 55 degrees) and I'm planning on using the system when the weather gets about 85 degrees. All those numbers told me that I would need about 17 sq ft of copper. When I did the calculations for 1/2" copper tubing it came out to about 130 feet of copper tubing will have a surface area of about 17 sq ft. I think I did the math right, but I could very easily have slipped a decimal point. :-) The idea of using plastic is possible, but I'm concerned that I would need significantly more to get the same cooling. Your mention of slowing the water flow to allow longer time to equalize the temperature is an idea, however I haven't seen any information about how to calculate that. BTW: I'm in Eastern NY near the Massachusettes border, and I used a 3 ton AC system as my goal based on pure SWAG (Scientific Wild A** Guess). I have a 2 story 2500 sq ft house. A 36,000 BTU system appears to be common, although i understand that due to insulation, windows, wall space, etc, etc etc. I may be over/under sizing the system. It looks like if I go with a commercial evaporator coil I could go with a 5 ton coil for about $100 more than the 3 ton, so I might do that just in case I wish to beef up the system if I'm undersized. And of course, just adding more copper in the pond. :-) MM