I have seen the radiator idea. It worked but having old black radiators in the yard looked like carp. A neighbor of mine used black plastic pipe hung on a south facing fence. Maybe five hundred feet or so. Worked well and didn’t look that bad. You would need a very stout fence to support that much weight.
This. We have always used a reel and it is easy enough for one person to operate and remove from the pool area. Once the pool gets warm enough, we will even leave the blanket off to cool the water a bit.
Also consider that in the summer of 2005, Natural Gas traded at between $7 and $13 per decatherm at the Henry Hub (most liquid price discovery point), whereas it is currently trading at about $2.68/dt spot with future contracts no higher than $2.79 through September.
Into the pool. But the difference is that the skimmer and filter had removed them at the same rate as they were added, and the pool was pristine clean at the time you wanted to go swimming. Pull the cover off and suddenly the pool was not pristine clean, but had a cloud of dirt wafting thought the water and dry leaves floating on top. Much depended upon how long it had been between swims, but it was something I disliked.
I recommend the solar blanket, but since you don’t like that, I would suggest using the rolls of the plastic drip-line tubing. Available in very long lengths. Its black, gets nice and hot, lasts for years and won’t leak a drop. Adapters for both hose and pipe fitting are available. And its cheap.
We used this stuff or something like it:
http://www.poolcenter.com/heater_solar_poolstor.htm
You can link as many sections together as you want, leave them on the ground or mount them on the roof and plumb the rig into the filter system. It would make the top 6" of water almost too hot to touch if the floor drain wasn’t working.
I once heard of a guy who covered his pool in ping pong balls instead of a blanket. Kids loved it - these might even be better from a kid point of view.
IFF you have a spot of level ground within easy reach of the pool and IFF your SO allows it…get some 1/2" black PVC pipe and make a serpentine layout of about 20 pipes 10 ft long, get the water to it with a 5-10 watt pump. Use black heavy duty garden hose to get the water to/from the matrix.
Works well–a friend did this in the Denver burbs.
Here is a link to some variations: http://greenterrafirma.com/diy-solar-pool-heater.html
I laughed. The first one is funniest because it’s real, of course, but the other is good too.
Get a 55 gal, drum-cut it in half, drill 2 small holes in top for anchor chains- float 1/2 barrel in middle of pool-build a fire in the barrel, heat until pool is warm.
Pumping pool water X* gallons per minute through the attic would be too risky for me.
The Prefect household has a 30’ diameter above ground pool. We’ve tried solar covers and solar panels before investing in a pool heat pump from PoolHeatPumps.com. Best four grand** we spent. Pool is comfy. No CO2 is released (Manitoba being a dam powered province) and I don’t have water coursing through my house 
One other option, if you have central A/C is a heat transfer dealeo that uses your pool water to take the heat from the house instead of the radiator of the A/C. The problem with that system, is the same as the problem with solar panels, they only work when it’s hot out. When it’s cool, like it is at night, they don’t do squat.
*drawing a blank on what X is, thinking it might be 50 gpm
** We did an assessment, large surface area, AGP, no solar cover (kept blowing off and wanted to see the water when hanging on the deck) all added up to needing one of the biggest heat pumps they sold. You may, with your IGP be able to purchase a less expensive option.
I do wish I had bookmarked this one:
Guy had an engineer in-house (he or his dad) and a propane barbeque grill. The calc showed that 2 bottles of propane would raise the water as much as desired.
Solution:
Very careful measurements of the inside of the BBQ hood, a bunch of 1/2" copper pipe and EL and what are called Street EL - a pair make a u-turn with no filler. He soldered up a pyramid-shaped mass of pipe which set on the grill and allowed the hood to lower. He ran the water from the filter into the heater. Don’t remember if he bothered to plumb it back into the pool return or just ran a line directly from the BBQ into the pool.
This was a masterpiece of getting as much pipe into a given space - and iit worked. Mid-sized gunnite pool in a moderate temp area.
I probably found it a TroubleFreePool (this is another endorsement) - but, even if not, someone there can probably point you to it.
When talking heat:
How many gallons/what kind of pool (even inground has a Q - fiberglass ve gunnite), nuber of degrees you want to raise.
I have no experience with “solar cover” - but my info is that they will not last more than 2-3 years.
There is a reason for people selling the roller mechanisms - I’m guessing they got tired of replacing the material.
Another thought:
Tankless water heaters - these raise water temp a bunch by burning lots of gas in high efficiency burners.
Normally sold for residential uses, they have good reports as room heating via baseboard radiators.
Again, gallons * desired raise.
Our friends have a pool in the garden. They also have a grassy area on a slight south facing slope. They buried black plastic pipe a few inches under the grass in a pattern spread out over a fairly large area. Add a small pump, and the pool temp is raised by several degrees when the sun shines.
From my experience, the gas heater is exactly as expensive as you think it will be but it works much better than any other solution.
Other solutions involving pumping water through solar panels or attics or whatever else end up costing more than you think they will, require not-infrequent repairs, and never work as well as you’d hoped. Solutions that involve putting stuff on top of the pool are a pain in the a** and never work nearly as well as you’d hoped.
Unfortunately I think this is a “You get what you pay for” situation.
The web page linked shows them stacked…
My fault for not reading - the "redneck pool heater"referenced above is the one I was describing.
Aside from the trouble to assemble all those fittings, it is a slick solution - you don’t harm the BBQ (except for inlet/outlet holes in the hood just above the grill), installing and removing it is a 1-person job. Copper lasts forever, and a good burner comes close.
I’d go with a tankless if I ever get to giving a damn about this disaster in the backyard - I do wish they had put in a roof BEFORE the solar collectors and skipping the spa and upgrading the crappy floors, doors, and hardware.
Anyone here use the PoolDisk beside picker? Do you get what you pay for?