Screen effect on water temp

[thefisch]

Moved from here.
Sorry to necrobump an old thread but this is on point to same question I have and it seemed better than starting a new thread.

So I've been searching for solar radiation info on the Phifer 18x14 versus the 20x20, but they only seem to have the info on their solar guard products. Anecdotally, I am hearing from screen installers that you could notice a slight drop of 1 or 2 degrees due to reduced sun exposure if you choose 20x20 over 18x14. One installer said the difference would be 5 degrees which would be significant in my book. But none of them had data to back that up.

 

[duraleigh]

For the future, it is always better to start your own thread so you get answers directly applicable to your situation.

A five degree drop is far closer to the truth. No data, but my relative's pool, an hour South of Orlando, required a heater running most of the summer to get to swimmable temps. The location was mostly sunny but with maybe 25% shade

 

[setsailsoon]

I'm further south of you and not sure what mesh size mine is but the installer called it "medium". He recommended I avoid the very fine mesh since it can also eliminate the breeze. In our case this works great. Bugs dive bomb us as soon as we exit the enclosure but inside we are bug free. We often leave the house doors wide open and eat outside at the table with no no-seeums or any bugs at all. We've had the screen for 7 years and seen no deterioration yet but I've heard the screen material will need to be replaced around year 10. Small price to pay for year round use of the pool!

Chris

 

[thefisch]

Thanks for making this it's own thread. Wasn't sure whether to do that or not.

A five degree drop is far closer to the truth. No data, but my relative's pool, an hour South of Orlando, required a heater running most of the summer to get to swimmable temps. The location was mostly sunny but with maybe 25% shade

And thanks for sharing your relative's experience. What temp to they consider to be swimmable?

Our pool has full sun from about 10am to 2pm at this time of year. See photo below taken today at 3pm looking NW. The house is starting to shade the pool.



In the summer, the arc of the sun moves enough to where we have no shade from the house until late. The sun sets in the summer right between the chimney and tall palm seen to the left in the photo. It can get pretty hot out there during those months. Normally the pool stays above 78F from June to September without supplemental heat. The water can easily get into the low 80's during the hottest times.

I'm further south of you and not sure what mesh size mine is but the installer called it "medium". He recommended I avoid the very fine mesh since it can also eliminate the breeze. In our case this works great. Bugs dive bomb us as soon as we exit the enclosure but inside we are bug free. We often leave the house doors wide open and eat outside at the table with no no-seeums or any bugs at all. We've had the screen for 7 years and seen no deterioration yet but I've heard the screen material will need to be replaced around year 10. Small price to pay for year round use of the pool!

Chris

If you have noseeums outside the pool cage and they are not getting in, then you might have the 20x20 screen or something fine than 18x14. Not sure what size 'medium' mesh is either, I think the largest opening is 18x14 threads per inch which is the cheapest screen. So maybe medium screen is a little finer than 18x14. Or they make screen with thicker strands which leads to smaller openings or screen with more threads per inch which also leads to smaller openings.

If you look closely at the weave pattern of the screen, you might be able to tell what kind by whether you see rectangle openings (18x14 inch) or square openings (20x20 per inch).

 

[thefisch]

Also, I thought I would share some closer photos of the pine straw that gets stuck in the 18x14 screen on our roof. That's one of the reasons why we are considering 20x20 on the roof. Reduced solar heat is one of the pros/cons we are looking into.





For background on why we are looking at 20x20 for the roof of the pool cage, see below for info posted in another thread here.

Our 'mansard' style pool cage is about 16 years old and the Phifer 18x14 screen has held up well for the most part. Can't complain after getting 16 years considering the FL sun and annual pressure washes. Now we have about 14 panels that should be replaced due to silvering, small tears and fraying at edges - since more will likely follow soon we are considering rescreening the whole cage.

Bugs have not been a huge issue with the 18X14 screen. We do get some (well the spiders and lizards get them mostly) but with conservation in the back, the screen door in use, the drain channel open on both ends (would love to screen that in) and some potted plants inside the cage, there will always be bug instrusions. Thankfully the noseeums are not a real issue where we live.

We love our view and the 18X14 screen helps that view, but there are some downsides. We have pine trees in the conservation behind our home and those needles always find their way through the roof screen. Also, in the rainy season, we will get clusters of bugs (ants or thrips - not sure) clinging for life on the surface (Dawn mixture is not their friend). Sharing those concerns with a few screen installers brought up the option of the Phifer 20X20 noseeum screen on the roof. Perhaps getting 20X20 screen on the 1200 sqft. roof might help with those issues - not eliminate them of course.

However, I understand there are downsides to 20X20 screen. Airflow is somewhat reduced - the walls would still be 18X14 so that should help with airflow. Apparently it is common to mix screen sizes or thickness based on needs. Another issue is the shading effect - not sure how much solar radiation is reduced but I understand that 20X20 screen will drop the pool temperature by a few degrees compared to 18X14. That might shorten the swimming season or increase the demand on the heater. I am also concerned that if it takes longer for the lania to dry out after a rain then it will lead to increased mildew growth. I realize that additional shading can be a benefit too - there are always tradeoffs.

Has anyone made the switch from 18X14 to 20X20? What was your before and after comparison? Any pros or cons that I missed?

 

[duraleigh]

What temp to they consider to be swimmable?

Roughly 82

 

[thefisch]

Roughly 82

Yeah, we would only get there with solar radiation for about two months of the year. I could see why they would need heat with more shade. Thanks again for sharing their experience.