Pool Cover Log

[SoCalTFP]

Hey Everyone I finally broke down and purchased a pool cover because we were losing so much heat and water overnight with the high temperature we like to heat our pool to. I don't mind the cost, well I do but tell myself the enjoyment is worth it, but I'd prefer to not go through the mental gymnastics of deciding if firing up our gas heater is worth it every time we plan to use the pool. I plan to log some general information for myself and figured someone who's trying to determine if a pool cover is worth the trouble might benefit as well so I'll post up information in this thread.

Background:
We have a ~12k pool/spa that we've owned for the past year in the inland Southern California area. 2 months back we fired the pool guy (after the second algae bloom and major scaling issues) and take up the TFP method. We have plaster finish, IC40 SWG, VSP, Raypack Gas Heater, and a Cartridge Filter. My kids started summer break so I keep the pool heated to ~85 daily, and then crank it up to 90-92 when the adults plan to swim because we like it hot. I have been noticing a large amount of evaporation with the low 50's night temperatures and have been topping the pool off every couple of days instead of weekly, which obviously is also contributing to a massive heat loss. I've been avoiding the Pool Cover since I remember them being a pain and my time is valuable enough that wrangling a sheet of bubble twice a day didn't sound worth it. My wife recently started talking about adding Solar and after some research it sounds like even that route a pool cover would be highly recommended.

A couple of days ago we received the pool cover I ordered. We have a kidney shaped pool with raised overflowing spa. I bought a 16x24 8-mil cover that covers about 80-90% of our pool/spa with some minor overlap on the sides. I planned to do-it-yourself roller with the foam piping and clips that seemed popular on here if needed, and potenially get a second cover to get the spa and non-standard sides that the current cover doesn't cover. Both of those will be based on the next few weeks of testing.

6/21/2023 Log:
I've been timing myself on putting the cover on and off the past couple of times, by myself it takes me less than 4 minutes to put it on and take it off. This morning I rolled it up and we have some outdoor storage that I should be able to place it in to keep it out of the sun and from being an eyesore. Overall my experience with taking it on and off has been extremely easy considering how many people mention they really struggle with these.

Last night the pump shut off ~6pm and was reading 92 degrees for the pool. This morning when it turned on ~6am (circulates water for morning testing) the temp was 87 degrees. I'll be simulating the same temperatures and leaving it off overnight for a couple of nights to log the uncovered temperature loss as well. We're starting off with a full pool (just below refill piping) and will track fill frequency and potentially do some uncovered tests as well.

Free Chlorine (tested with FAS DPD daily) is usually 9-9.5ppm based on CYA 80 without the cover and 0 CC. This morning it was 8.5ppm FC and 0.5ppm CC. I will continue to monitor this but at first glance my assumption is the cover is potentially leading to the slight increase in CC. Also this could just be a minor testing discrepancy. I'll be tracking this because I'd like to better understand how the cover impacts chemical usage in the event I'd like to leave it on during a vacation or if we'd like to stop removing the cover daily in the winter to retain heat for the occasional weekend "pool hot tub" party. PH is 7.6, although I'm a little color blind so I'm never fully confident on that test for .1-2 accuracy.

Given the ease of removal and "close enough" fit I will likely push out my plans to build the DIY roller and custom fitting it to the pool for another week or two unless something changes. My kids are too small to remove it and my wife likely won't want to, so it's pretty much going to fall on me.

My plan is to update this daily (or maybe every couple days). If nothing else it will help me keep my thoughts straight and help someone who's been considering a cover but not sure if it's worth the trouble.

 

[ajw22]

CC rise with a cover on is normal. That is why you need to remove the cover occasionally and let the pool breath and burn off the CCs.

The cover traps CC so only test CC after the cover has been open with sun shining on the pool surface for several hours.

Some pics of your pool would give us more context to those who will follow this thread.

 

[SoCalTFP]

CC rise with a cover on is normal. That is why you need to remove the cover occasionally and let the pool breath and burn off the CCs.

The cover traps CC so only test CC after the cover has been open with sun shining on the pool surface for several hours.

Some pics of your pool would give us more context to those who will follow this thread.

Thanks ajw22 I'll adjust my testing schedule to grab a cleaner test after the CCs have burned off. I'll likely continue to grab them after I pull it off as well because I'm interested in seeing the trends on CCs for any future longer term covering scenarios.

I'll also add some pictures of the pool and how I have the cover on there, as well as any meaningful changes. Great idea thanks for calling that out.

Quick update I pushed the temp to 92 again yesterday and left the cover OFF overnight to compare to yesterday's results. The temp this morning is 85, I'm going to see where it stands in an hour to get as close to the same time. Less heat retained than I was hoping TBH.

 

[SoCalTFP]

Here's a few shots of the pool. I'll add some with the cover on there when I get it on next as well.

Looks like the temp is settling in this morning WITHOUT the cover on overnight at 84, which means about 3 degrees of additional temperature loss without the cover. Weather conditions were similar to yesterday's. When I get some time I plan to do some calculations of gas usage to heat the pool and local gas rates to understand what the heat retention of the cover works out to from a cost savings perspective. I plan to maintain the temperature all summer in the mid-high 80's and then bump it up to around 90 for pool parties or extended adult swimming sessions so I'd imagine even minimal cost savings will add up over the course of the month. A set temperature of 92 is on the high end for us so I'd imagine all of this would loosely fall inline with the sources I've read about the cover cutting the overnight temperature loss in half with a more reasonable high 80's target temperature.

At first glance I'm imagining the ROI is probably acceptable. A few degrees retained probably isn't a massive cost savings but it likely would add up over the month, and if I start to see some large impacts on the heavier evaporation I've been seeing since we started heating that should put it over the top. That said if it took much more time than the ~4 minutes to pull it off in the morning when I do my general pool routine, and ~4 minutes to put it on when I'm cleaning up at night, it might not be worth it. Another reason that a cheap/thin/light cover is probably the best route if you're considering one since the 8-mil is completely manageable.

I also plan to extend our swim season out as much as possible, and potentially look at keeping the cover on 24/7 in the winter with removal on the weekends when we want to swim in the winter months if I'm able to retain enough heat. I saw an interesting thread a while back about someone who was doing this in much more extreme winters (snow region) and with proper cover/pump management able to heat to the mid 90s while keeping gas usage bearable in Jan/Dec.

FC/CC testing this morning was as expected with the cover off comparison, 11/0 (my CYA is 80 due to the SWG). Having dealt with an algae bloom leading me to TFP I run my SWG at the top end of the recommended FC range but I'll cut this down a little bit if PH testing becomes a part of this for any reason to ensure the 10+ FC doesn't impact those tests.

One other note I run the spillway for an hour daily during daylight hours (when the cover will be off now), 30 minutes AM/30 minutes PM. I'll post anything related to how I manage this with the cover on once I get there. I'm planning to try letting it spill onto the cover first, then adjust RPMs for a trickle if that doesn't work, and then cut to allow spilling from there if needed. I may also take that as an opportunity to try adjusting the automated spillover time down (I've got general PH rise issues) and testing the Spa side independently to ensure proper chemical mixing.

 

[SoCalTFP]

Another night with the cover OFF, I had a minor medical procedure done and will be able to start lifting it again today so it will go on tonight. Last nights ending pool temp was 84 degrees, this morning was 78 so about 6 degrees lost overnight. We likely won't be cranking the heat up this weekend so I can see how this compares with the cover on as well. Nothing meaningful to report on today's chemical testing since I'm more interested in tracking FC/CC relationship while the cover is on.

Time permitting I may be tackling a DIY Roller this weekend. I was planning on following this thread's method unless anyone has a better suggestion. Figured I'd run 2 pieces of pipe ~12ft each to make it more manageable. Totally open to any suggestions here though if anyone has them.

DIY Solar Cover Roller

Someone in another thread had asked about how I built my own solar cover roller. So here it is. Initially, I had purchased a SolarRoller and it worked pretty well for about three years after which the aluminum pipe corroded through. So I looked at several alternatives and came up with the...

www.troublefreepool.com

 

[SoCalTFP]

Fell asleep early last night and forgot to check me evening temp, and left the pump (and heater) on so can’t really use any of that data unfortunately. Pentair tracks it all in the history but I haven’t figured out how to really drill into it much with it being an iOS app.

Here’s a couple of pictures of the covered pool. I ordered the materials for the DIY roller for Lowe’s pickup but considering canceling it. Starting to feel like I’m about to do an hour or two project to MAYBE save a couple of minutes a day. I may just push that out a few weeks and see how working with it with no roller goes.

As you can see I haven’t trimmed it yet. It looks like if I do I might be able to use the scraps to get the rest of the pool and get a seperate round cover for the spa. That said not needing to mess with which side is which when unfolding it is nice right now.

Overall my feedback is positive for working with this thin cover on a smaller pool. If it was much bigger it would be a PITA though.

 

[SoCalTFP]

Also forgot to write up the most notable part of this log, which is kinda turning out to be uneventful and I might stop in a few days. Surprise, pool cover is probably worth it especially if you can easily manage the size.

My dog ended up taking a dip in the pool, he didn’t realize the cover wasn’t solid. Scared the Crud out of my wife who was in the jacuzzi. I spent so much time explaining the dangers to the kids that I forgot to show the dog something new was on there. Probably an unexpected benefit since now we’re making him get in and working with him to ensure he’s a competent swimmer and knows where the steps are to get out.

Lesson learned here is make sure your pets understand what the cover is if you use one!

 

[SoCalTFP]

No major updates. Seems like I’m seeing about 3 degrees temperature loss overnight with the cover on consistently, which is roughly half without. Napkin math for gas usage puts this around $100 a month savings. Even if that’s way off the cover more than pays for itself. Evaporation also seems greatly reduced but it’s been difficult to actually track that.

I skipped the DIY roller, seemed like more trouble than it’s worth for a pool this size. No sense spending an hour or two on a frustrating project to save a minute or two a day.

I also skipped cutting and filling in the gaps. Seemed easier to not have to worry about positioning it correctly, especially since it covers 90%+ of the pool surface. May add a round one for the spa later.

We’re holding consistent mid 80’s pool temps with high 70s daytime and low 50s night temps. It’s about to heat up here so we’ll probably be near the target adult swim temperate of low 90s with low/no heat.

CC testing following removal in the AM has also been zero the past few days. The kids and I also got to remove a hissing beatle the other day which probably would have been in the skimmer, so a little added 7am fun to the day.

I’ll be tracking AM and PM temps in pool math and will post logs up when I get some time if anyone is interested. I’ll likely update this less frequently unless anything interesting pops up, since I’m sure “it’s hot AF outside and my pool is hot Af too” will get boring as the summer heat sets in. I’ll post more frequently near the tail end of the season when any findings around extending our season or winter usage is impacted.

Overal verdict so far is worth it for energy/heat savings. Might not be worth it if I calculated out my personal time, but I don’t mind putting it on and taking it off. Especially because throwing $$$ away every time we jack the heat way up would probably bother me more than folding up bubble wrap.

If you have a similar sized pool and are on the fence it’s worth a shot. If your significantly bigger you might want to consider roller options or multiple pieces. 16x24 8-mil has been zero issues by myself though.

 

[KJB1]

I noticed a big increase in retained heat and lower chlorine loss when I used one. The downsides are a hassle to remove and store (very easy to talk yourself out of a quick dip), dirty pool(debris sinks rather than skimmed), not visually appealing and the last was danger to our dog. It went in the trash after a year or less.

 

[SoCalTFP]

I noticed a big increase in retained heat and lower chlorine loss when I used one. The downsides are a hassle to remove and store (very easy to talk yourself out of a quick dip), dirty pool(debris sinks rather than skimmed), not visually appealing and the last was danger to our dog. It went in the trash after a year or less.

Yea the pet situation is something people should consider heavily. Our pool is enclosed which helps, I think ours would already be in the trash if he was able to roam free around the pool.

EDIT: When I get some time tomorrow I’ll write up some thoughts on the general safety considerations I’ve noticed. I think the general concerns are well documented but I’ll share my findings here as well too. We have 4 small children so I spend a lot of time considering the safety/security of our pool these days.

 

[SoCalTFP]

Thanks to the response from @KJB1 I realized I've been missing some general thoughts on the safety with the pool cover on. As most are probably aware (but I won't assume in case someone stumbles on this), the pool becomes much more hazardous with the cover on. It can be difficult to get out of a pool wrapped in plastic bubble wrap and I'd imagine would significantly increase the risk of drowning if someone or something accidentally ended up in it. This is compounded when the cover is untrimmed if oversized, since it could be pretty easily overstep into the pool itself.

Our family has 4 kids all under 7 years old, so we are accustomed to viewing our pool as a fun death trap. We have a pool gate, sensors on all exterior doors and the gate itself, cameras, and get notifications from all of them on our phones/watches/computers and the smart home announces any of these being opened. Since my other hobby is smart home and security, and my wife is a sucker for anything that protects our family, I'll likely end up expanding all of this further. So from our perspective the pool is a major hazard for a toddler, regardless of if it's covered or not. The changes we've made to increase safety with the cover on have only improved safety when the cover is off as well.

For those of you that don't have small children or pets that don't swim, your uncovered pool may not be as big of a concern. Putting a cover on it instantly increases the risks and the level of vigilance you need for those around it. Even a gated pool accidentally propped open for an unsuspecting pet, or a teenager who lazily only uncovers half the pool, could be a drowning hazard.

So something to consider beyond the energy or convenience factors. For our case we're able to minimize the risk, which we learned early, but we're already dedicating a lot of effort to pool safety that others might not be required to do.