Necessary to heat salt pool when opening early?

[jbpete]

Hi Everyone,

I am in Utah and this is our 3rd season with a salt water gunite pool. We wanted to open the pool a little early to work on the pool chemistry for a few weeks before it warms up. Temps in the low 40’s at night. Pool water is about at 45 upon opening. I was told since we opened the pool early we need to be heating the pool to at least 60 degrees due to the salt water generator. I am fine to do it if needed but would rather not if it’s unnecessary. I searched the forum before posting and didn’t see an answer to this particular question. Would love any help or advice on if this is true.

 

[proavia]

You don't NEED to heat it.
Just use liquid chlorine until the SWG is operational.

 

[PoolGate]

Saltwater generators typically will not work below 55 degree water temp. If you want your SWG to work, then you could heat to 60. That could be expensive and as proavia said, just use liquid chlorine until the temp raises on its own.

 

[SJPoe]

My SWG is after the heater, so the water going across the SWG cell is far warmer than the overall pool temp.

When I 'soft opened' - I set the heater to like 55, which was enough that the outflow from the heater was around 65, and the SWG was quite happy making FC at that temp.

 

[generessler]

Note that most heaters warn that continuous operation at low temps (for mine it's 68F) causes corrosive condensation and voids the warranty.

I find tabs are very handy for this situation, since CYA is often low early in the year anyway, and they keep pH down. A couple in a floater last nearly two weeks for me, so CYA doesn't rise much anyway. A 10lb bucket lasts a few years.

 

[SJPoe]

Heater Condensation - Further Reading

www.troublefreepool.com

 

[jbpete]

Thank you everyone for your help and advice! This was all great information. I will use some chlorine tabs for now to save some $ until the weather heats up.

 

[EmilyOTR]

are chlorine tablets recommended in this situation? We are opening early this year due to a problem but we like the idea so much I think we will open early every year so we will be faced with this issue. this site is not a fan of those. plus how do you add CYA while using it?

 

[SJPoe]

are chlorine tablets recommended in this situation? We are opening early this year due to a problem but we like the idea so much I think we will open early every year so we will be faced with this issue. this site is not a fan of those. plus how do you add CYA while using it?

There is nothing inherently wrong with Chlorine Tabs - you just need to be aware that they add CYA along with Free Chlorine.

If your CYA is already low (which is often is at opening time), then using tabs to tide you over until its warmer is fine - just calculate how much CYA you are adding so you don't end up with more than you want

 

[Newdude]

If your CYA is already low (which is often is at opening time), then using tabs to tide you over until its warmer is fine - just calculate how much CYA you are adding so you don't end up with more than you want

And the timing matters too. Say you open with little CYA. With tabs dissolving slower than usual with cold water, it may take weeks to get to the 30 you were targeting. Your FC will deplete quickly during that time, possibly inviting an algae bloom.

SWG folks who closed with much higher CYA likely have at least some of it left at opening to protect the FC in the short term. They are in no rush to raise CYA to 70 for the peak season so they can wait out the tabs if they take a few weeks, providing they had 30+ to start.

 

[EmilyOTR]

interesting. we generally close with a lower CYA i think. I know i know, but I don't test it often. i generally have virtually nothing at opening. I could add some towards the end of the season and then maybe this would work. although maybe 30 is what I have and to me that's virtually nothing lol.

There is nothing inherently wrong with Chlorine Tabs - you just need to be aware that they add CYA along with Free Chlorine.

If your CYA is already low (which is often is at opening time), then using tabs to tide you over until its warmer is fine - just calculate how much CYA you are adding so you don't end up with more than you want

as far as calculating, that's the issue, how much will the tabs add?

 

[MITBeta]

as far as calculating, that's the issue, how much will the tabs add?

Use Trichlor in PoolMath to figure this out. Each tab in 8 ounces.

 

[Newdude]

we generally close with a lower CYA i think. I know i know, but I don't test it often.

You don't need much CYA in the late season as UV loss plummets.

. i generally have virtually nothing at opening.

So bump it to 30 with granuals then use the tabs as much as you'd like the rest of the way.

Overnight Chlorine Loss Test at 30 before proceeding though. This year you're SLAMing and will be passing an OCLT already before moving on. Make it a habit to never add significant CYA without the OCLT.

as far as calculating, that's the issue, how much will the tabs add?

Go to the upper left menu in poolmath and click effects of adding. MITbeta just beat me still typing. Lol

 

[SJPoe]

Pool Math is your friend :

 

[wayner]

Note that most heaters warn that continuous operation at low temps (for mine it's 68F) causes corrosive condensation and voids the warranty.

Do you mean when the water is below 68F or the air temperature is below 68F? And if it is the water then would you be running it that much when the water temperature is below 68F? Once you get the temperature to 68F then it would never be running continuously below 68F, unless you shut it off for several days.

FYI - I will run my heater, which is a Raypak NatGas heater, to heat up my water at the beginning of the season when the water is below 68F until it gets into the 80s. But it probably only runs for a few hours until the water hits 68F.

 

[generessler]

Do you mean when the water is below 68F or the air temperature is below 68F?

Yeah. Iiuc, cold water running through the heat exchanger causes water in the exhaust gases (when you burn just about anything, water is created) to condense inside the heater, and it's very acidic. So it eats up the exchanger (although I've seen info recently that some Hayward heaters manage water temp to prevent this problem). So the guidance is to limit the time in this state. Either don't use the heater until the water is 68F or more, or get it from less than 68F up to that temp quickly and keep it there. The temp can vary by brand due to differences in the exchangers.

Heater Condensation - Further Reading

www.troublefreepool.com

 

[wayner]

I read that link. It says:

Manufacturers say prolonged operation with water temperatures below 50°F is not recommended. When starting the heater with water temperatures below 50°F, operate the heater continuously until higher temperatures are reached. Operating the heater for prolonged periods with pool water below 50°F can seriously damage the heater, and is not covered by the warranty.

If this happens once, or once a year, it is no big deal and there shouldn't be any significant damage. But if you do this regularly, for example daily for weeks or months at a time, it will significantly shorten the life of the heater.[3]

So it seems like it isn't a big deal if it is just once per year. And with some heaters it is below 50F, which must be pretty extreme. I am in Toronto and when my pool opened a few days ago it was 53F, now it is 57F.

But how would you ever operate the heater for weeks or months at a time with the water at a cold temperature? Even if I turned my heater on now, heated the water to 85F then it would be good for a few days. It would take several days for the water to go back to the 50s, if it even got that low. So I don't know how your heater could operate for weeks or months when the water temperature is in the 50s. I have seen places in cold climates with pools, but I presume that they have massive heaters that can keep the water in the 80s. I once swam at an outdoor pool in Quebec City in February where the outdoor temperature would have been around 0F.

Reading that article about heater condensation - Pentair Heaters seems to be particularly finicky about this. Pentair says below 68is a problem, Jandy says below 40, Raypak says below 50. Those are big differences.