A Chlorine Floater? Can This Work?

[kbaumann]

I am wondering.... could I use a chlorine floater and close it air tight... then drill two holes above where the tabs would sit and yet below the water line... The holes could be as small as 1/32 (.031) maybe... inside the floater put unstablized chlorine tabs... This would make it so the chlorine is introduced into the spa very slowly? Maybe?

[bart6453]

I am wondering.... could I use a chlorine floater and close it air tight... then drill two holes above where the tabs would sit and yet below the water line... The holes could be as small as 1/32 (.031) maybe... inside the floater put unstablized chlorine tabs... This would make it so the chlorine is introduced into the spa very slowly? Maybe?

That's a negative Ghost Rider....the Trichlor is acidic, and will drop your PH drastically.

[chem geek]

There are no unstabilized chlorine tablets unless you count Cal-Hypo and that tends to fall apart quickly and increases Calcium Hardness (CH) which would cause scaling. As noted with Trichlor, it is very acidic and it will also dissolve too quickly in hot water and increases Cyanuric Acid (CYA). For those that want automated dosing, they usually go with bromine whose tablets dissolve much more slowly; for chlorine, automated dosing needs a pump or, for pools, something like The Liquidator.

[quantumchromodynamics]

I use trichlor in a modified feeder sometimes. I use the Pentair model 335 Chlorine / Bromine Floating Dispenser. I close the feeder all of the way and then drill a few holes between the bars. I use only 1 tab at a time and it lasts for about 10 days. I recommend that you not use more than 1 or 2 tabs at a time.

Each tablets weighs about 0.5-0.7 oz. This will provide between 0.86-1.2 ppm per day and will raise cyanuric acid between 0.5-0.7 ppm per day. (Assumes a 400 gallon tub).

If your alkalinity is high enough then the pH will be OK. You need to be careful opening the feeder because there will be concentrated chlorine in the feeder that will be let out when you open the feeder. You need to open it over a bucket or something that can catch the concentrated chlorine water.

It is important to know that trichlor will increase your cyanuric acid and it will lower your pH if the alkalinity is not high enough. Once your cyanuric acid gets to about 30 to 50 you will have to discontinue using trichlor.

I think that it can be used in a limited way for a limited time. Some trichlor tabs dissolve too fast, but there are some that will last for about 10 days. You should add bleach to make up the rest of the chlorine demand based on tub usage.

[chem geek]

So using this very slow Trichlor introduction to handle when the tub is not in use, but use bleach (or MPS if using N2 with that approach) after each soak to handle bather waste sounds reasonable. As you say, one has to watch the pH, but if the non-bather chlorine usage is around 1 ppm FC per day, then the rate of CYA rise from the Trichlor would be around 18 ppm per month and actually somewhat less than that since CYA does slowly break down, so perhaps 13-15 ppm increase per month. As you say, this seems OK for a limited time, but not for more than a month or two (of course, this is still a vast improvement over the Dichlor-only method that has the CYA rise much more quickly).

It's too bad that a ready-made dispenser somewhat calibrated for this purpose isn't made. I would also be very careful about where the floating feeder parks itself since the water around the feeder can become very acidic. I rusted out some stainless steel mounts in my own pool by having such a feeder park itself nearby. Just that experience alone would have my shy away from using a feeder again, even for short-term purposes.