Retrofitting Hot Tub with SWCG. Worth it?

DangerBoy

Well-known member
Oct 5, 2018
51
0
Calgary/Alberta
#1
Since learning how SWCGs work I've become curious about the economics of retrofitting hot tubs with such a system and what systems are available that are appropriately sized for hot tubs. So far my investigations have only lead me to find drape over systems, some of which claim to be "smart" (able to detect when they should be generating chlorine or not). A drape over system wasn't exactly what I had in mind. I would prefer a system I could insert into the circ pump/heater plumbing circuit inside the pump compartment of my tub so everything's contained and out of sight in the pump compartment. Are there any systems like that available anywhere? If yes, can you point me towards it/them?

From what I've learned, it seems you have to replace the generator cells every so often and they're kind of expensive. Given that chemical and reagent costs of operating a hot tub using the TFP system and using regular bleach, baking soda, muriatic acid and borax instead of overpriced chemicals from a spa store are not huge, my guess is you'll never save enough in chemical costs to even approach paying the costs of obtaining and operating the SWCG system. Am I correct in that assumption?

If the economics aren't there then the only other thing that could justify converting to a SWCG system would be convenience and ease-of-use. It would be worth something to me to eliminate the nearly daily need for FC testing and bleach top-ups. It would be nice to have a system that eliminated the need for that and reduce it down to perhaps weekly testing just to make sure everything's kosher with the water conditions and chemical levels in the tub. Is this something that's attainable with a SWCG system?
 

Jimrahbe

Mod Squad
LifeTime Supporter
TFP Expert
Jul 7, 2014
10,186
2
Bedford, TX
#2
db,

I have the simple "drape-over" unit and love it. It was less than $200 bucks and works just fine. (Looks like they have gone up to about $230...)

I treat my small spa just like my pool. Once set up, I basically add nothing but MA... The cell has a timer and runs for 8 hours starting when we are normally done soaking.. This increases the FC so that it never drops below my minimum. I keep an eye on my CC's and when they get above 1.5, I'll add some liquid chlorine.. As a general rule this does not happen very often, if at all... I do drain and start over every three to four months..

I wanted something that was easy to install and replace and would not mess with the factory plumbing.. Also very easy to clean...

Here are a couple of pics..

The control panel....



The cell....



Thanks,

Jim R.
 

DangerBoy

Well-known member
Oct 5, 2018
51
0
Calgary/Alberta
#3
That system looks interesting and the price is pretty reasonable. I just don't like the idea of a drape over system as the winters are very cold here and draping a thick cord over the lip of the tub would interfere with the cover's ability to seal to the tub and result in considerable heat loss. Perhaps if I can find a way to route the cable into the filter compartment from the pump compartment by drilling a hole through the filter comparment wall a safe distance above the waterline, I could eliminate that problem. I'll have to take a look but it might be possible to do. I'm not using the old Ozone generator that came with the tub and I'm pretty sure no longer works so I've got an unused 120V power source I could tap into to power the thing so it's all self-contained inside the tub. Failing being able to use the ozonator power supply, my GFCI subpanel has a 120V breaker on it that's not being used so that's another possible 120V power source for it.

How many hours are the generator cells on those units rated for and how much do they cost to replace?
 

Jimrahbe

Mod Squad
LifeTime Supporter
TFP Expert
Jul 7, 2014
10,186
2
Bedford, TX
#4
db,

The cord to the cell is smaller than a pencil, and does interfere with my insulated cover..

Cost to replace the cell is about $100 bucks. I've had mine running at least 8 hours a day for about two years. It could go south tomorrow, but as far as I can tell it appears just fine.

The manual says it is good for 7,000 "normal" use hours... Does not say what that is...

If mine went bad today, I'd have another one on my porch tomorrow. :D

The only problem with mounting it inside the spa, is that would make it difficult to change the operating hours..

It appears to me like this is a Canadian Product... eh!!

Thanks,

Jim R.
 

GamecockTim

Well-known member
Feb 12, 2016
54
0
Fort Mill SC
#7
I've placed my bet on the Chlormaker Megachlor system with Chlorine detection for my new spa. The idea is that it will produce 2 ppm Chlorine in a 30 min cycle and shuts down until the hot tub falls below 2 ppm then runs another cycle. So the hot tub will automatically cycle between 2 and 4 ppm Chlorine with minimal runtime on the SWG, preserving SWG life.