Putting in a SWG early next week...

[Lithium406]

So, I decided to finally pull the trigger on a SWG system and it's going in early next week. I've been playing around with the numbers on the pool calculator thing, and I'm slightly concerned with regards to the CSI...

Here are my numbers using Trichlor...

pH - 7.6-7.8
TA - 80
CH - 270
CYA - 60
Borates - 0
Water temp - low 60s
CSI - .05-.24 (depending on pH)

When I add salt to the mix, it throws the CSI off, and if pH drops at all, it sends the CSI close to .60.

I guess what I'm asking is for those of you who run your pool year round and use a SWG, what numbers do you shoot for to keep things balanced? During the summer things should be more in line, but the cold water is magnifying the problem.

 

[linen]

One mitigating factor is as the water cools, its ph will go up some...so in your case, that is a good thing. See chem geek's post here: http://www.troublefreepool.com/csi-and-cold-water-t20769.html Also, swgs tend to raise ph, though you may not have to run much in the coldest part of the winter. Additionally, cold water reduces the rate at which plaster will dissolve. I think you are fine for the winter. Keep in mind, most swgs will not run when the water goes down in the lower 50s, though you also would not need much chlorine then, especially if the pool is covered.

 

[Lithium406]

Thanks for the quick reply.

That makes sense, but since I want to leave my pool open all year with no cover (my hot tub is attached to my pool), why would I not run my SWG during the coldest parts of winter? If it's not running, will I have to manually add chlorine if I want to use my hot tub?

 

[bobodaclown]

You'll always want some residual chlorine in your pool if it's open/uncovered year round. During the winter when the water is cooler (if you don't heat the pool) your daily chlorine demand drops.
Do you have separate plumbing for the spa/pool or does it spill over/separate spa return?
Do you keep the pool heated for the whole winter?

Are you planning on installing the SWCG before the pool/spa return or on the pool only return?

Others can provide some better answers. I don't have a spa but to keep my CSI in manageable slightly negative numbers (0 --0.3) (I have to run my CH higher (425) to maintain proper CSI. I have a plaster pool and a SWCG.

 

[linen]

Having a cover will reduce the chlorine lost to the sun, which is typically the major chlorine usage in the winter.

why would I not run my SWG during the coldest parts of winter? If it's not running, will I have to manually add chlorine if I want to use my hot tub?

Depending how cold your water gets, it may not run...most will not run below water temps of 50F. Good news is, either way your pool should use a lot less chlorine at the low temps and acute sun angle, so even if you have to manually chlorinate (with bleach/liquid chlorine), it shouldn't be nearly as much as during the summer.

As bobo asked, can you isolate your water flow for the tub from the pool?

 

[ping]

I let my SWG run all year but my water rarely drops below 62 degrees. You can run your SWG all year long if it does not shut off due to the water being too cold. What you will notice is that you will need to adjust the pump time and SWG output % as the water drops in temp.

If the SWG will not produce chorine due too cold of water, then you will need to add liquid chorine to maintain the proper level of FC. The good part of adding liquid chlorine during the winter is that it lasts much longer than during the summer.

 

[Lithium406]

You'll always want some residual chlorine in your pool if it's open/uncovered year round. During the winter when the water is cooler (if you don't heat the pool) your daily chlorine demand drops.
Do you have separate plumbing for the spa/pool or does it spill over/separate spa return?
Do you keep the pool heated for the whole winter?

Are you planning on installing the SWCG before the pool/spa return or on the pool only return?

Others can provide some better answers. I don't have a spa but to keep my CSI in manageable slightly negative numbers (0 --0.3) (I have to run my CH higher (425) to maintain proper CSI. I have a plaster pool and a SWCG.

The way my pool is set up is I have one return in the spa (fountain) which causes it to overflow down the spillway, but I also have 6 or 7 return jets in my pool as well. 50% of the return goes thru the fountain and 50% goes through the returns in the pool. Hopefully that makes sense.

I only want to be able to turn on my hot tub during the winter months; I wont be heating the entire pool. When I turn on my hot tub, it changes the returns so the pool returns (including the hot tub fountain) are off. Everything flows then flows through the 6 or 7 returns in the hot tub.

It's going to be installed in the same place that my fusion system is currently installed.

regarding the CSI/CH, that's what I was concluding as well - increase the CH.

 

[linen]

Is there a filter on the hot tub water circuit?

 

[Lithium406]

Yes. At least, I'm pretty sure that it does. When I turn on the spa, it sucks water from the two drains at the bottom of the spa, runs it through the Fusion 2 system (about to be a SWG system) along with the DE filter and then returns it via the six return jets

 

[bobodaclown]

I don't think the SWCG will have enough run time to keep the water in the spa chlorinated properly with the heat and bather load. You may have to manually add some chlorine to bump it up right after usage. A SWCG is great for maintaining chlorine levels, but not for raising it quickly. When ever we are going to have a party I try manually dose before and after the party.

What's your pools pump daily run time? Is that with water running to the spa also? Remember that the cell output is based on 24 hour run time. I think most people run their pool pumps around 12 hours or less. I run mine 8.

Do you have 2 separate pumps? 1 for the pool and 1 for the spa? I bring up these points so you won't be disappointed with the SWCG. They are a great time saver for maintaining the pool chlorine level.

I just want to make sure I understand. Poolpump pumps water to pool and Spa, and it spills over back to the pool. There is no 2nd pump. When you use spa mode it shuts off the pool returns and powers all the jets in the spa. If that is the case you may have to manually dose after spa usage. When you shut off the spa and go back to running the pool pump will it mix the pool water and the heated spa water?

Also your SWCG will be after the filter, heater and solar panels correct?

 

[Lithium406]

I don't think the SWCG will have enough run time to keep the water in the spa chlorinated properly with the heat and bather load. You may have to manually add some chlorine to bump it up right after usage. A SWCG is great for maintaining chlorine levels, but not for raising it quickly. When ever we are going to have a party I try manually dose before and after the party.

What's your pools pump daily run time? Is that with water running to the spa also? Remember that the cell output is based on 24 hour run time. I think most people run their pool pumps around 12 hours or less. I run mine 8.

Do you have 2 separate pumps? 1 for the pool and 1 for the spa? I bring up these points so you won't be disappointed with the SWCG. They are a great time saver for maintaining the pool chlorine level.

I just want to make sure I understand. Poolpump pumps water to pool and Spa, and it spills over back to the pool. There is no 2nd pump. When you use spa mode it shuts off the pool returns and powers all the jets in the spa. If that is the case you may have to manually dose after spa usage. When you shut off the spa and go back to running the pool pump will it mix the pool water and the heated spa water?

Also your SWCG will be after the filter, heater and solar panels correct?

I understand. That makes sense.

I run my pump for 7 hours a day during the winter time, and I only have one pump.

As far as my system, when it's in "pool" mode the water drains from the deep end of the pool and the two skimmers, runs through the equipment and then returns it back to the pool via the returns in the actual pool and also through the one return in the spa which is a fountain. The spa then overflows down a rock spillway back into the pool. Now, if I switch to "spa" mode, the water begins draining from the two drains in the hot tub, run through the equipment and then returning through the returns in the spa only - the pool is essentially off in this case.

That's correct, THE SWG will be after everything else before returning to the pool and/or spa.

What I'm gathering that I need to do is manually add some chlorine to the spa before I use it when it's super cold outside OR let the spa run for a short while before we get it. My thought process there would be that once the heater gets the spa water temperature up to 51* the SWG will kick on and start chlorinating the spa. Given that it has much less volume than a pool, it should get up to acceptable chlorination fairly quickly, right?

 

[Poolsean]

If you put the generator cell before the valve to switch between pool or spa, there's the possiblity of overchlorinating the spa. It really depends on how often and how long you're in the spa when you do use it, and which manufacturer and what size cell you go with. Most systems shut down when temps fall below 55-60 degrees. Autopilot does not, and will continue operating, regardless of temperatures. The Automatic Temperature Compensation feature will adjust the output % based on water temperature changes, and lower it to 1% when it gets to 55 degrees or colder. As temperatures increase, it will automatically increase the % as well.
If its used for frequent parties, where you cram it with people, even a swg running at full output may not keep up with the chlorine demand, and as Bobo recommended, you will need to manually supplement chlorine to the spa.
But for normal family spa usage, having the cell on with little usage, may possibly overchlorinate.

With the generator cell plumbed in the pool return line, if you and your family just occasionally use it for about an hour, there should be enough residual chlorine in the water from the pool to the fountain (spa) to safely use the spa. Then, when you're finished and turn the valves back to normal operation, the spa water will flush into the pool and replenished with chlorinated water.

Your assumption though:
"What I'm gathering that I need to do is manually add some chlorine to the spa before I use it when it's super cold outside OR let the spa run for a short while before we get it. My thought process there would be that once the heater gets the spa water temperature up to 51* the SWG will kick on and start chlorinating the spa. Given that it has much less volume than a pool, it should get up to acceptable chlorination fairly quickly, right?"
with most salt systems shutting down under cold water conditions, you'll need to manually add chlorine to the pool, which in turn will treat the spa too. Then when the heater gets the temperatures above the cold water protection threshold, the salt system will turn back on and provide chlorine for the spa. How quickly though, will depend on the manufacturer, size cell, and output setting. In most cases, a typical 800 gallon spill over spa shoudn't take more than an hour at 100% output, to crate a safe chlorine residual.

 

[Lithium406]

So I just went out and checked and the flow goes like this...

Pump -> Multivalve -> Filter -> Multivalve -> Heater -> Fusion 2 (soon to be SWG) -> Valve that sends it to the pool and fountain in the spa or, if the spa is on, to the spa returns.

By over chlorinating the spa, you mean when it's in spa mode it's just pumping chlorine like crazy into only the spa, right? If so, that's what you'd want in a spa though, correct? With lots of people in a small space and warm water. I'm not sure what you mean by autopilot though...

Your second statement (regarding my "assumption") seems to contradict your first, so I'm confused now. Haha.

 

[Lithium406]

Here's what I'm working with...

 

[bobodaclown]

Beautiful pool. Overall it sounds like you're good to go. Remember to test your water often especially PH and Chlorine Levels (TC/FC). Once you get a feel for your chlorine demands you'll be better off. Overall I don't think you'll be disappointed.

 

[Lithium406]

Thanks everyone for all your input. One more question though...

Why are the FC requirements are less with a SWG pool than they are with a non-SWG pool?

60 CYA = 5-7 FC in a Trichlor pool
60 CYA = 3-4 FC in a SWG pool

 

[RobbieH]

Because the water gets superchlorinated as it passes through the SWG.

That fountain will drive ph up too by the way.

 

[Lithium406]

Because the water gets superchlorinated as it passes through the SWG.

That fountain will drive ph up too by the way.

Ah. Ok. Thanks!

With regards to the fountain, I thought it would too, but it really doesn't as much as I think it should. Throughout the summer I've added ZERO acid, all I've added has been washing soda to get the pH up. I figured that the fountain (raising pH) + the trichlor tablets (decreasing pH&) would give me a fairly stable pH of around 7.6, but it was ALWAYS dropping (7.2-7.4) even though my TA was consistently maintained around 80-100.

 

[linen]

When you move to the swg, your will see more ph rise (some from the swg itself). The tabs are very acidic.

I am surprised and somewhat skeptical that your cya is only 60 ppm unless you have done a partial drain/refill.

 

[Lithium406]

I did a 50% water change about a month or so ago because the CYA was at about 110. I got the pool installed less than a year ago, so I figured I needed to do a water change every six months or so.