Can someone explain the economics of proper opening and closing to me?

[primuspaul]

I was reading some pool opening and closing instructions on this site, as well as some discussions of the topic, and I just can't get the economics of it to make sense. Typically the choices are:

1. Winterize the pool so that all you need to do is refill and adjust chemicals a bit the next time pool season starts.
2. Accept the water will turn green and drain/refill it.

I checked my water bill and it's basically $200 greater the month I have to fill up the pool than the rest of the months of the year. So what's the economic theory behind winterizing the pool? From what I read, you have to close after temps go below 60 deg F and open before they go over 60 deg F. One poster noted this means opening up in March/April and closing around November. This translates to adding about 2 months of pool operating costs to pool season which around my part of the world is generally around 4 months long (as far as inground outdoor unheated pools are concerned).

Am I missing something? That's 2 extra months of electricity and chlorine, as well as wear and tear on the pump equipment, during which time few people will want to use the pool due to the water being generally cold. Not to mention the extra work to clean the pool and raise the chemistry to the winterize levels, which often includes unusual chemicals like PolyQuat. Isn't it cheaper and easier to just open in late May with new water, eat the $200 bill (and it's actually less of a difference than that since even the winterizing option requires some significant pool draining and refilling so we're talking $100-$150 difference at most), and close in mid-September? Then the only extra step is pressure washing the green stuff off the walls after draining and before refilling, which is not a terribly difficult task.

Also with new water I'm free to use cheap trichlor tabs as opposed to expensive cal hypo (which has its own problems) and liquid chlorine until I reach the desired CYA. If I keep the old water and am the right CYA already trichlor tabs are no longer an option unless I do a significant water change to dilute it.

 

[JohnT]

Draining and refilling an inground pool, particularly in the spring, is fairly high risk of damaging the shell.

Very few pools have any CYA after the winter.

 

[primuspaul]

Draining and refilling an inground pool, particularly in the spring, is fairly high risk of damaging the shell.

Very few pools have any CYA after the winter.

How does a drain damage the shell? Does it apply to concrete pools? Also how does the damage appear? I've had a corner fall out of the pool (top of the pool), but it was a fairly easy fix.

 

[ajw22]

If it works for you then do it.

People have lots of different situations as to ability to drain their pool, local regulations on disposal of pool effluent, availability of clean fresh metal free water, ability to wash a pool surface, available time to supervise the drain and refill, etc.

You dump a lot of good chemicals during a drain - salt, calcium, borates - that you have to get back into the pool after a drain. For example, my pool needs over 20 bags of salt after a refill and about 5 bags of salt on a spring opening.

You can choose to spend your time and money one way or the other. Choose wisely.

 

[Eauclaire]

To minimize chlorine demand between early September to early November, I cover the pool with a dark tarp which inhibits photosynthesis and stop all circulation and chlorination. The water stays clear and a fine sediment appears on the bottom, which I drain in November when winterizing - I need to remove 35% of the pool volume to accommodate snow and rain volume over the winter, so I have plenty of water to work with. Concrete municipal pools are emptied in late August and refilled in mid June.

 

[TopJimmy]

I’ll leave my pool “open” this winter. It was a bit of a hassle to winterize and dewinterize for Nov-Mar. I’ll set the heater to 70 deg. I have an autocover so it’s no problem

 

[Bperry]

How does a drain damage the shell? Does it apply to concrete pools? Also how does the damage appear? I've had a corner fall out of the pool (top of the pool), but it was a fairly easy fix.

Pressure washing can damage plaster and draining can dry it out, which both damage it.

Fiberglass and vinyl pools can float (or float the liner) or have walls shift if there is no water to support them.

If you run a single speed pump then the electricity costs could be excessive for a couple extra months, but running mine at very low speed 24x7 doesn’t even register on the electric bill especially when we have AC running.

Closing chemicals are none for me. If the water isn’t frozen, I’ll put a floater with a trichlor tab in it just for insurance. I didn’t even cover the pool last winter so I put the robot in all winter except for when it froze over. (I actually forgot to take it out before it froze over).

It seems to be all downsides and no upsides in letting it turn swampy over the winter.

 

[primuspaul]

To minimize chlorine demand between early September to early November, I cover the pool with a dark tarp which inhibits photosynthesis and stop all circulation and chlorination. The water stays clear and a fine sediment appears on the bottom, which I drain in November when winterizing - I need to remove 35% of the pool volume to accommodate snow and rain volume over the winter, so I have plenty of water to work with. Concrete municipal pools are emptied in late August and refilled in mid June.

But do you still run the pump during this time?

Pressure washing can damage plaster and draining can dry it out, which both damage it.

Fiberglass and vinyl pools can float (or float the liner) or have walls shift if there is no water to support them.

What if I have concrete? Do the same rules apply or is draining/refilling in Spring safe for concrete?

If you run a single speed pump

I do.

then the electricity costs could be excessive for a couple extra months, but running mine at very low speed 24x7 doesn’t even register on the electric bill especially when we have AC running.

What sort of pump is this? Also what about the wear and tear on the pump?

Closing chemicals are none for me. If the water isn’t frozen, I’ll put a floater with a trichlor tab in it just for insurance. I didn’t even cover the pool last winter

So you didn't cover the pool and without adding chemicals or running the pump during winter it didn't turn green? Seriously?

so I put the robot in all winter except for when it froze over. (I actually forgot to take it out before it froze over).

It seems to be all downsides and no upsides in letting it turn swampy over the winter.

Perhaps TN is a bit warmer than my part of the country.

 

[Bperry]

But do you still run the pump during this time?


What if I have concrete? Do the same rules apply or is draining/refilling in Spring safe for concrete?

If your pool is plastered concrete then yes that’s a risky task to drain it. Maybe if it’s completely tiled, there’s different issues.

I do.

What sort of pump is this? Also what about the wear and tear on the pump?

A variable speed pump running low speed doesn’t take much more power than a light bulb (not the LED kind. )

So you didn't cover the pool and without adding chemicals or running the pump during winter it didn't turn green?

The robot cleaner picks up leaves and junk that falls in, and I check the chlorine once in a while and add a tablet to a floater. I also don’t close the pool until December when the water is 50F and that helps.

Seriously?

Perhaps TN is a bit warmer than my part of the country.

I’m sure that helps. You can drop a sump pump in the water to circulate chlorine once in a while if it’s still liquid. My point was really that the two options you presented are not the only options.

 

[primuspaul]

If your pool is plastered concrete then yes that’s a risky task to drain it. Maybe if it’s completely tiled, there’s different issues.



A variable speed pump running low speed doesn’t take much more power than a light bulb (not the LED kind. )


The robot cleaner picks up leaves and junk that falls in, and I check the chlorine once in a while and add a tablet to a floater. I also don’t close the pool until December when the water is 50F and that helps.


I’m sure that helps. You can drop a sump pump in the water to circulate chlorine once in a while if it’s still liquid. My point was really that the two options you presented are not the only options.

Can it run through a sand filter on the low setting? At that low power draw it makes sense to just get a pump like that and run it 24/7 to make up for the low rate of flow, even during the summer.

 

[PoolStored]

Can it run through a sand filter on the low setting? At that low power draw it makes sense to just get a pump like that and run it 24/7 to make up for the low rate of flow, even during the summer.

Yep, and get this...it will filter better at slow speeds!

Oh, and if you have an SWCG, it will make chlorine all throughout the day!

Lots of us run low speed, 24/7.

 

[SoDel]

If the economics of closing and opening are interesting to you, then you may want to gain some experimental experience with your own pool before deciding what’s better or best. For example, my pool gets closed the end of October with a solid safety cover and opened early May. I close late and open early for the dual purpose of having cold water while it’s closed and preferring looking at the water to looking at a cover. The water never turns green over winter and a couple days of running the filter, letting the robot loose and chlorinating is enough to bring it back to clean and crystal clear. A neighbor has a mesh cover and the only added step she deals with on opening is manually vacuuming the pool a couple times. Where you are is even colder than where I am so you may be overthinking the process. It might make sense to confirm you have a problem before you set out to solve it. In other words, don’t sweat all the algae fears; just close the pool, open it in Spring and see if anything more than that is really needed for your pool.

 

[primuspaul]

If the economics of closing and opening are interesting to you, then you may want to gain some experimental experience with your own pool before deciding what’s better or best. For example, my pool gets closed the end of October with a solid safety cover and opened early May. I close late and open early for the dual purpose of having cold water while it’s closed and preferring looking at the water to looking at a cover. The water never turns green over winter and a couple days of running the filter, letting the robot loose and chlorinating is enough to bring it back to clean and crystal clear. A neighbor has a mesh cover and the only added step she deals with on opening is manually vacuuming the pool a couple times. Where you are is even colder than where I am so you may be overthinking the process. It might make sense to confirm you have a problem before you set out to solve it. In other words, don’t sweat all the algae fears; just close the pool, open it in Spring and see if anything more than that is really needed for your pool.

Is it true that Chlorine does not deteriorate in pool water as long as sunlight does not hit it?

 

[TopJimmy]

Depends on a variety of factors, of course. But to give an idea of an ideal state of balance:
Thru experience to maintain my FC: when cover is open I have my IC40 set at 40%. When closed it’s at 4%.

 

[ajw22]

Is it true that Chlorine does not deteriorate in pool water as long as sunlight does not hit it?

No. That is not the only chemical reaction that consumes chlorine.

A closed pool with a solid cover will still lose chlorine over time.

 

[primuspaul]

No. That is not the only chemical reaction that consumes chlorine.

A closed pool with a solid cover will still lose chlorine over time.

What about the lack of sunlight and algae growth? Does it prevent algae from growing?

 

[ajw22]

What about the lack of sunlight and algae growth? Does it prevent algae from growing?

You seem to be looking for absolutes here.

Nature and chemistry works in strange ways.

Cold water and darkeness tend to keep algae dormant. However like may species algae finds ways to survive and sometimes thrive.

 

[Newdude]

Plus, either safety cover when dry will billow in the wind. While direct sunlight is off the water, some small amount of UV will still get in there.

 

[Eauclaire]

I deploy my solar blanket and cover it with a black tarp making sure it is snug up against the pool wall. I stop circulation and chlorination for 8 to 10 weeks (late Aug to early Nov) and never have had algae. I remove all covers for winterizing in early November.

 

[Saturn94]

No. That is not the only chemical reaction that consumes chlorine.

A closed pool with a solid cover will still lose chlorine over time.

Not to mention even a fresh bottle of chlorine will degrade even if you never open it.