It was normal boring evaporation.

[kul]

Hi friends! Recently we have been getting a lot of rain so I haven’t had to add water to my pool in some time, but have had to drain afterward to protect coping and get water back to middle of skimmer level. During the last few weeks, I thought I noticed evaporation at a higher rate than it was in December/January so I decided to do the bucket test. I still have 6 hours to go before I reach the 24 hour mark. At this time, I’ve lost 1/8” in the pool and maybe 1/16-1/8” from the bucket. The bucket is an orange Home Depot bucket submersed half way on first step and was filled to about 1cm below the top.

I wonder if this amount of water loss has just been normal and maybe I just never investigated? The water temperature has been pretty consistently around 56-58. Night outdoor temp is usually upper 40s/low 50s and daytime is typically upper 60s/occasionally low 70s with a mix of sun/overcast. Maybe some more days with mostly sun, but I haven’t kept track of full sun days vs overcast/sun.

I don’t have any visible leaks at plumbing pad and no air issues in pump. No bubbles at returns. No wet spots around the pool.

I’m just surprised to be even losing this amount of water during the winter. We do get wind, frost, etc. Can anyone confirm that this is typical for them?

 

[ajw22]

When nighttime air temperatures are below water temperature you get more evaporation.

Cold nights cause evaporation.

 

[kul]

Maybe that is what’s happening. I thought evaporation was due to when water is warm and the daytime temps are high (like 75 and above) with full sun. I hadn’t considered temperature differences at night. In fact I thought cold temps were protective against evaporation!

So maybe this is night time evaporation…it’s not much evaporation, but it seemed atypical.

 

[Bperry]

Maybe that is what’s happening. I thought evaporation was due to when water is warm and the daytime temps are high (like 75 and above) with full sun. I hadn’t considered temperature differences at night. In fact I thought cold temps were protective against evaporation!

So maybe this is night time evaporation…it’s not much evaporation, but it seemed atypical.

You may also give it to her three days and see if there’s a big difference in the bucket test

 

[kul]

You may also give it to her three days and see if there’s a big difference in the bucket test

I’ll go ahead and check again tomorrow. What is an acceptable difference between the bucket and the pool evaporation? 1/8” or less? More? What would be considered a “big” difference?

I did this test with my pool running as normal which means pump is on for 6 hours (6am-12pm).

 

[Bperry]

I’ll go ahead and check again tomorrow. What is an acceptable difference between the bucket and the pool evaporation? 1/8” or less? More? What would be considered a “big” difference?

It’s not a very precise test. There’s a big tolerance between what you can lose in the bucket and the rest of the pool. But if you had an inch difference between them, it would be a really strong indicator that there’s a leak. It’s hard to even measure anything smaller than an eighth of an inch when talking about water level and a plastic bucket, and in the pool.

 

[kul]

@Bperry thanks for clarifying. It certainly is not easy to see the difference between 1/16 and 1/8. My eyes were fooled a couple times by the clear TFP water.

 

[ajw22]

@Bperry thanks for clarifying. It certainly is not easy to see the difference between 1/16 and 1/8. My eyes were fooled a couple times by the clear TFP water.

Put some duct tape inside the bucket and pool to indicate the starting level.

 

[kul]

Put some duct tape inside the bucket and pool to indicate the starting level.

Yes I do have the tape on both so that does help. It’s if the water moves that I have a momentary confusion. Shouldn’t be off by much either way so I’ll keep an eye on it tomorrow to see if there’s much difference.

Based on my measurement today, it does seem reasonable based on my observations during the past few weeks that it could be that I’m losing 1/8” inch per 24 hours.

 

[ajw22]

1/8 per 24 hours is normal evaporation

 

[oldprophet]

Yes I do have the tape on both so that does help. It’s if the water moves that I have a momentary confusion. Shouldn’t be off by much either way so I’ll keep an eye on it tomorrow to see if there’s much difference.

Based on my measurement today, it does seem reasonable based on my observations during the past few weeks that it could be that I’m losing 1/8” inch per 24 hours.

Loosing 1/8 " of water day would not be an indication of a pool leak, and I used to live in LA

 

[Bperry]

Yes I do have the tape on both so that does help. It’s if the water moves that I have a momentary confusion. Shouldn’t be off by much either way so I’ll keep an eye on it tomorrow to see if there’s much difference.

Based on my measurement today, it does seem reasonable based on my observations during the past few weeks that it could be that I’m losing 1/8” inch per 24 hours.

I found it easier to sink the bucket just above the surface and then fill the pool up so the level just spills over into the bucket and ensures the level inside and outside the bucket is the same. Then it’s easier to see the difference. But yea, 1/8” is pretty normal.

 

[Newdude]

Are you still using the solar cover ?

 

[kul]

I am not using a solar cover at this time. I’m waiting until maybe end of April or beginning of May to put it on because I go through one cover each swim season.

Thank you everyone for the reassurance. I checked again and the amount lost between the bucket and the pool remains at 1/8” during the last 24 hours. I’ll leave my experiment going through tomorrow, but if it stays stable I’m going to chalk this up to normal evaporation.

 

[Newdude]

I am not using a solar cover at this time.

Put it back on (for now). If you get a week with no rain and the pool doesn't budge, you'll feel much better about it.

 

[kul]

I measured again today and it was the same as yesterday. Both the bucket and the pool lose 1/8” over a 24 hour period, so I’m going to go with no leak and normal evaporation primarily in evening/overnight when air temp is lower than the pool water temperature.

@Newdude I think I’m going to hold off on the cover because 1) it’s a whole scene and 2) we have sporadic rain forecasted the next couple of weeks. I might do it after rain is not forecasted for at least a week. But I might also just chill out about it since the bucket and pool had the same evaporation. I don’t have much pool stuff to do so maybe I’m just looking for experiments.

 

[Newdude]

Both the bucket and the pool lose 1/8” over a 24 hour period, so I’m going to go with no leak and normal evaporation primarily in evening/overnight when air temp is lower than the pool water temperature.

Sweet. I personally don't like the bucket for small losses. If the bucket isn't full as described above, the wind doesn't hit the water in the half (?) empty bucket the same as it does the pool. Or maybe it doesn't make the same ^^^^^^^^^^^^^ ripples to match the pools, even if its full.

But it sounds like you'll be fine.

1) it’s a whole scene

Oh I KNOW. I had a work/hate relationship with mine. I freaking HATED that it worked.

 

[kul]

If the bucket isn't full as described above, the wind doesn't hit the water in the half (?) empty bucket the same as it does the pool.

Yeah I see what you mean. The bucket was submersed half way and I had filled it up to the top (1 cm) below lip. I see last day of rain forecasted is Saturday 3/2 so will throw the solar cover on after that for a few days to observe.

 

[kul]

@Newdude alright, impatient as usual, I went ahead and put the solar cover on. This year’s cover is slightly smaller than I usually buy so some of the perimeter is exposed. I did this so I wouldn’t have to cut strips like I usually do and maybe yank it off/on with less work. I’m doubtful about the less work part, but it made sense while I was overthinking it last season. I also went ahead and bought a back up cover because they were cheaper on Amazon by $30 than what I paid last year.

Anyhow, I’ll watch the evaporation for the next 24 hours and will report back.

Should I do the whole bucket situation again or just mark the outside of the bucket only?

 

[Newdude]

alright, impatient as usual, I went ahead and put the solar cover on.

I wouldn't expect it any other way. And same.

This year’s cover is slightly smaller than I usually buy so some of the perimeter is exposed.

You'll lose proportionately that much efficiency. If 10% is exposed you'll have 90% less evaporation than uncovered. Maybe even a little more efficiency because the small exposed areas probably won't ripple as much in the breeze.

Anyhow, I’ll watch the evaporation for the next 24 hours and will report back

When it doesn't lose any noticeable water, let it go until it rains next because such little loss will mess with you in the short term. You'll feel great about it when you're still trying to decide if it lost any 8 days later. Sometime soon you'll have a stretch of good weather if this week isn't great.

Should I do the whole bucket situation again or just mark the outside of the bucket only?

I'd skip the bucket and go with extended cover testing. You have time with such little loss. No need to overanalize the poor bucket.