I was afraid of your results :-(  

I kind of lost you with the test with the water bucket, - if you leave water out in a bucket in the sun it will heat up, so you kind of lost me on what the water bucket has to do with the solar system... the water is not moving, so it has no other choice but to heat up, and if there is no water flow at all as there would be in a pipe, then it's natural the water will become hot.  Anyway I just lost you on that test I guess.  Do I need another cup of coffee here ? or can somebody clue me in LOL :-)

My pool is an 18 foot above ground, and without any solar stuff running on
it, it heats up about 3 degrees per day I get sun from about 10am until 6pm
now,
used to be about 7:30pm but now with the shorter days sun is gone by 6:30pm
max, and it's not strong at 6pm nowadays.

With my solar heaters running  - I made 3 of them using 1/2" black pipe -
each is about 500 feet coiled up..... anyway
with those running I get just over 1 degree per hour of temperature rise,
which is of course with the sun's passive heating also.
I figure 1 degree an hour is not bad though, I wish it was more, but i"m
only pumping in a tiny bit of water, compared to the thousands of gallons
that are in that pool.

Temps though for example: ... if the pool is 73 degrees, and if the sun is
shining full strength, I get a 88 degree temp coming from the black tubes,
each one is separate.... meaning all of my tiny solar systems are 100%
independant of each other.

Anyway if I drop the flow, then the temp can go much higher.... but if the
flow coming out of those tubes was only say 2 degrees higher than the actual
pool
temp - it's really a lost battle.

Each of my 3 homemade solar systems made with 1/2" black tubing are pushing
6 liters of water per minute.
for a total of 18 liters per minute.( all 3 combined )

To calculate what that is in gallons per minute I used the following
forumula:
18 liters divided by 3.8 ( 1 U.S. gallon ) = 4.7 gallons per minute.

Anyway, with this little flow, I got quite a few emails from people saying
that this system is basically useless, - the temps are GREAT,
but I need bigger flow.

In order to heat my pool I need a good temp increase - a good 10 degrees
above the actual pool water temp, PLUS a lot of water flow.

Seeing this, I decided to buy a professional solar panel and am thrilled
with it.  I have bought the same panel my brother's friend bought,
and he has to actually turn the thing off because his pool gets too hot !
.... on a hot sunny day he can get his pool up by 5 degrees in only an hour,
pretty darn good - but remember the tube he's using is a 1-1/2" tube - like
the one in your project, but water coming out of it is hot enough to almost
burn you
he said, -  and flow is very fast from what my brother noticed, and the pool
was 94 when he went into it a few weeks ago, so with my brother's being in
the pool and
telling me that the water was indeed 94, and that the water from his panels
was that hot, I had to take the plunge and buy the same system, a lot more
money than doing
it yourself though that's the part that sux.

Anyway I posted images on it .........

http://www.fieldlines.com/story/2003/8/22/1942/51667

Tim, I think that you did a great job on that piping though I love the
concept - I'm going to try a homemade one like you did, but will use small
piping in the middle
to connect pipes together, - so it's made like the professional ones....
check out this tubing and how cheap it is....... one of the guys on the
forum directed me to it,
this is just the tube I'm looking for !