To protect the cover from deterioration, is it necessary to have the cover COMPLETELY off the hot tub after adding chemicals?

[Davekro]

We are instructed to keep the 'Cover Off' for 5, 10, 15, 20, mins after chemicals are added while the 1-2 pumps are circulating to allow for the initial high off gassing period. Is it just Chlorine and Dichlor that this is important for (w/ a chlorine tub) to lessen gas damage to the underside of the cover? Or is it just as important when adding the occasional .5 to 1 oz of Mur. Acid 31.45% also? For the Bromine folks, is the answer the same?

Because I do not have my cover lifter installed yet, I have usually just opened the cover half way while running the pumps to circulate 1-2 oz. of added chlorine.
1) If you leave just half the cover open for the recommended time, is that just as good for cover life protection as all the way off?
2) Does the fact that the water's off gassing flows by and over half of the under side of the cover on its way out, constitute a noticeable ill effect on the underside of that half of the cover?
3) Is the fact that the gasses flow out and away, and are not trapped in a cloud between the water's surface and the cover perfectly fine for the cover. With the cover closed, I'd assume the trapped gas builds in strength and deterioration, harmfulness to the cover.
4) If in fact, having the cover only half open is unlikely to cause deterioration for the closed half of the cover, would just leaving one end of the cover held open, say 4", allowing the gasses to escape, be just a good as either half off or completely off?

Occasionally I forget I have the hot tub cover off or half off for hours after adding chemicals... Ooooops. IDK if a half open cover or a cover with say just one end propped open say 4" or so, would lose any less heat than the cover all the way off, but my mind feels more guilty if I left it all the way off for a long period.

Thanks for your thoughts.

 

[YippeeSkippy]

I do 30".... I include Muriatic Acid too.

 

[phonedave]

I sure it is somewhat detrimental. But sometimes I close my cover right after adding chems. Shhhh, don't tell anyone.

 

[BravoRomeo]

I've been leaving the cover half-open for at least five minutes after adding chlorine. The vinyl underside seems no worse for the wear on either side, and both sides have absorbed some moisture over the last five years. The Sunbrella fabric on the top side, however, is not looking so great after it was power washed a little too aggressively last year. I figured allowing ventilation is more helpful to the water (CC's).

Covers are a consumable. You can only delay the inevitable, a little, maybe...

When it's time to replace this cover, I'll look at some of the more hard-finish options instead of fabric. The tree sap is such a pain to get out of the fabric.

 

[phonedave]

I've been leaving the cover half-open for at least five minutes after adding chlorine. The vinyl underside seems no worse for the wear on either side, and both sides have absorbed some moisture over the last five years. The Sunbrella fabric on the top side, however, is not looking so great after it was power washed a little too aggressively last year. I figured allowing ventilation is more helpful to the water (CC's).

Covers are a consumable. You can only delay the inevitable, a little, maybe...

When it's time to replace this cover, I'll look at some of the more hard-finish options instead of fabric. The tree sap is such a pain to get out of the fabric.

I would love to find something that actually cleans mine. I have tried a number of things and they all clean it a little, but nothing really seems to get the dark stains out.

 

[SJPoe]

I've never bothered leaving the cover open after adding chemicals. For a big part of the year, it's too cold to leave it off - sub-20F air temp gets to the point the heater wouldn't even keep up...

That said, we've had the same cover since the hot-tub was new, and I cannot see any real signs of degradation - the outside is a bit grubby, but the inside looks pretty much the same as it was when it was delivered 2 years ago. Ours is a sort of textured vinyl inside, with a fabric outside, chlorine-based hot-tub.

 

[Mdragger88]

I also have no cover lifter.
I often only do the 1/2 open thing- especially in the winter. In the summer I try to let it hang out in the sun a while & give it a good rinse every now & then.
I have noticed that side that’s usually down looks worse so i started flipping it. That said, I had an issue where i had no cya for a while last winter & didn’t realize it that made the underside of my cover much less supple.

 

[Gebo]

I only leave mine open when slamming. If I’m adding a couple oz of liquid chlorine, leave it shut.

 

[Davekro]

I also have no cover lifter.
I often only do the 1/2 open thing- especially in the winter. In the summer I try to let it hang out in the sun a while & give it a good rinse every now & then.
I have noticed that side that’s usually down looks worse so i started flipping it. That said, I had an issue where i had no cya for a while last winter & didn’t realize it that made the underside of my cover much less supple.

Oye, your comment made me test my CYA. It was 48 ppm. I last tested 3 1/2 weeks ago and I got .6 ppm CYA. I had totally forgotten what CYA was about, so Googled it again and found chemgeeks CYA to FC chart and learned I needed to revise my target FC from 2-4 to 6-8 FC, and minimum FC from 2 to 4 ppm. I just raised the FC to 8.2 and will keep it between 6-8 ppm while occasionally checking the CYA.

What I don't understand is when there was little to no CYA, the FREE chlorine sweet spot was say 3 ppm. Now with a CYA of 48, the chlorine level needs to kept higher. It sounds like what is still called FREE chlorine, 8.2 in my case tonight, is by definition partially non working chlorine and partially chlorine able to do it's job. That latter portion would seem FREE meaning working chlorine, while the former is not really working. This now reminding me about when my tub was santized with Bromine and I had to create a Bromine bank to start off with, then add bromine along the way as it got used up. I did see the term 'bank' used in relation to CYA. I guess it is a similar thing with CYA/chlorine.

I am confused at what the 'bank' of CYA (or bromine) does compared to the chlorine we need to add to make the ever increasing "FC" sweet spot amount so the chlorine can do it's work. It seems like the last 3-4 ppm of the FC test result, at what ever FC level number, is all that is actually killing the bad guys.

 

[SJPoe]

What I don't understand is when there was little to no CYA, the FREE chlorine sweet spot was say 3 ppm. Now with a CYA of 48, the chlorine level needs to kept higher. It sounds like what is still called FREE chlorine, 8.2 in my case tonight, is by definition partially non working chlorine and partially chlorine able to do it's job. That latter portion would seem FREE meaning working chlorine, while the former is not really working. This now reminding me about when my tub was santized with Bromine and I had to create a Bromine bank to start off with, then add bromine along the way as it got used up. I did see the term 'bank' used in relation to CYA. I guess it is a similar thing with CYA/chlorine.

I am confused at what the 'bank' of CYA (or bromine) does compared to the chlorine we need to add to make the ever increasing "FC" sweet spot amount so the chlorine can do it's work. It seems like the last 3-4 ppm of the FC test result, at what ever FC level number, is all that is actually killing the bad guys.

@mgftp posted a reply the other day that explains the relationship between CYA and FC for sanitation very well - worth a read

 

[Mdragger88]

Oye, your comment made me test my CYA. It was 48 ppm. I last tested 3 1/2 weeks ago and I got .6 ppm CYA. I had totally forgotten what CYA was about, so Googled it again and found chemgeeks CYA to FC chart and learned I needed to revise my target FC from 2-4 to 6-8 FC, and minimum FC from 2 to 4 ppm. I just raised the FC to 8.2 and will keep it between 6-8 ppm while occasionally checking the CYA.

What I don't understand is when there was little to no CYA, the FREE chlorine sweet spot was say 3 ppm. Now with a CYA of 48, the chlorine level needs to kept higher. It sounds like what is still called FREE chlorine, 8.2 in my case tonight, is by definition partially non working chlorine and partially chlorine able to do it's job. That latter portion would seem FREE meaning working chlorine, while the former is not really working. This now reminding me about when my tub was santized with Bromine and I had to create a Bromine bank to start off with, then add bromine along the way as it got used up. I did see the term 'bank' used in relation to CYA. I guess it is a similar thing with CYA/chlorine.

I am confused at what the 'bank' of CYA (or bromine) does compared to the chlorine we need to add to make the ever increasing "FC" sweet spot amount so the chlorine can do it's work. It seems like the last 3-4 ppm of the FC test result, at what ever FC level number, is all that is actually killing the bad guys.

Not a bank persay but to put it simply, the cya binds some of the chlorine.
This does a couple things in a spa environment:
- Makes the chlorine less harsh (which is important for bather comfort & keeping equipment/surfaces in good condition)
but…
it also makes it less effective when equal fc amounts are considered.

Each fc level on this chart is equal as it pertains to active chlorine (ie. 3ppm w/20cya is the same “active strength” as 6ppm w/50 cya)

So for a standalone spa the sweet spot is 20-40 ppm cya.

Without cya the necessary fc level to keep the spa sanitary is lower but it is also harder to maintain without being harsh or falling below min or to zero.
as you know the bather load is quite high in a spa so 2 ppm can be used up rather quickly and unsanitary conditions can ensue. The smaller the spa & the more bathers the faster this happens.

So you want enough cya to buffer the harshness of the necessary free chlorine
& enough free chlorine that you don’t risk falling below minimum mid soak.