Retaining heat during cold snap - in addition to solar cover

[AndyTN]

First, I don't have a heater and my wife won't let me invest in one right now since we just paid off our new liner. I also don't have enough room near my pool to set up enough solar panels to make any difference.

With schools being shut down, I am desperate to entertain my 5 year old son and I have been obsessive with the pool water temp lately to allow him to swim on warm afternoons. I have been able to get my pool temp as high as 76 over the past few weeks which has been enough for my kid to jump in and for me if I have had a few drinks. Now looking at the forecast, we are going to have temps below 60 most of the week with some strange number of 34 for one of the overnight lows. I am concerned I will lose a bunch of my heat and we can't swim again until end of April.

Please let me know if you have suggestions to what I am already doing. I have a solar cover on the pool at all times except a couple hours in the afternoon on a sunny day. I put my winter tarp back on 2 days ago in anticipation of the 3-4 inches of rain we got yesterday so I was able to keep the ~ 1500 gallons of cold rain water from mixing in. I plan to only run the pump 3 hours each day when the afternoon sun is beating down on it, for the next several days. I plan to backwash before starting the circulation to push out some of the cold water in the pipes and sand filter.

Will I lose a lot of heat from the water circulating in the pipes under ground? If the air temp is below 60, will I net a gain in temp with sunlight absorption compared to the water flowing through the equipment above the ground? Should I put my winter tarp over top of my solar cover for extra insulation when overnight lows get down into the 30's?

I know this all seems like a lot of work to salvage 5-10 degrees of temperature but when you are stuck in the house with two kids who are 1 and 5, it becomes a desperate situation. I have even gone as far as to run a hose from our hot water heater to the steps so my son can have a warm-up zone while swimming.

 

[AndyTN]

Also, will my blue bubble solar cover be blocking some of the heat from the sun? It certainly allows light to pass through but at peak sunshine in the afternoon, would I be better off removing the solar cover even if the air temp is only 55? If we are not swimming, will we absorb/retain more heat with the solar cover on or off during afternoon sun?

I accidentally ordered a solar cover which is a foot too narrow so I do have a foot of surface water exposed the majority of the length of pool. I justify this now that it allows some of the water to breath and the skimmer still collects some of the Crud from the trees.

 

[Brett S]

I’m in Florida, so my climate is a bit different than yours. However, from my experience a month or two ago in trying to warm my pool up during the shoulder season here I discovered that leaving the solar cover on all the time (except when swimming, of course) was best to help warm the pool up. The cover seemed especially helpful in the afternoon when the sun is beating down on it. From my experience, the pool would gain a little more heat when the sun was shining and the cover was on, vs the sun shining onto an uncovered pool.

You may also want to run your pump a little more during the day as well. If your pump is off and you can feel that the first inch or two of water under the cover is significantly warmer than the rest of the water in the pool then you would definitely benefit from some circulation to mix that warmer water in. Ideally you want the water circulating during the day when the sun is shining on the cover and you don’t want to be able to feel a temp difference in that first inch or two of water. It takes less energy to heat the water from 75 to 76 degrees than it does to heat it from 85 to 86 degrees, so you want to try to keep colder water right next to the solar cover where the sun is working to warm it. I would suggest turning the pump on shortly after the pool starts getting full sun and not turning it off until evening when the sun is starting to go away.

 

[AndyTN]

I have a big oak tree over my pool blocking the sun until about 1 in the afternoon, which is also hindering my solar heating capability. I would just have the thing cut down but the tree is in a neighbor's yard. It does provide nice shade in the summer but it is a huge pain with leave and tannin stains in spring/fall.

I ran the pump only for about 2 hours the past 2 days due to high temps in the 50's and there was also a mix of cloud cover. I will check this afternoon to see how much heat I have lost but the pool has been mostly dormant the past 3 days. It was 85 here last WED and yesterday the high was only 51. We were certainly spoiled.

Good suggestion about taking temperature readings of the first few inches before starting the pump. I have a temperature gauge with a wired probe so it will be easy to test for a temp difference at 2-3 inches compared to 2 feet. I will also make sure my returns are pointed straight up to get the water moving at the surface as much as possible.