slow and steady chlorination idea- first tests

Beez · Posted: September 2nd, 2010, 5:36 pm

anonapersona wrote:

I've got a question, did the jugs manage to keep the FC level above some point? I am thinking that diffusion relies on a difference between one fluid and the other. So that as the FC near the jug got higher, then less chlorine would leave the jug. So, the jug might be a way to insure that FC never got below some level, 2 or 3 or something, although it may be harder to make the FC get to a higher level like 8 unless flow was really high near the chlorine source.

Not that I could tell. The jugs were submerged in the spa, which has very good circulation. Furthermore, it seems to me that the FC in the spa would have to climb to very high levels before it would slow the diffusion from jug to pool water. And that didn't happen...

Based on the rate of diffusion I observed over the last week, I would need approximately 10 open jugs in the pool to keep up with my chlorine demand. Not very practical...

Beez · Posted: September 2nd, 2010, 5:39 pm

Also, it seems to me that the rate of diffusion would decrease as the level of bleach in the jug decreases, but that may not be so...

Rangeball · **Joined:** May 25th, 2007, 4:00 pm **Posts:** 717

Is the rate of diffusion tied to the size of the hole or the area of contact between the water and the bleach?

I'm thinking of a 5 gal bucket filled with bleach then submerged. Say a 5" hole is cut in the lid. The area of contact between the bleach and water is 5". However, over time the upper area of the bucket becomes filled with water (as bleach is diffused), and the contact area between water and bleach is now the full diameter of the bucket. Is this greater contact area going to cause higher FC levels or will the 5" lid opening provide steady FC levels?

Bama Rambler · Posted: September 3rd, 2010, 10:33 am

Both and more. The rate of diffusion is controlled by the difference in concentration between the two and the surface area of affect. So, the larger surface area will diffuse more rapidly but then as the concentrations get closer together the rate slows down so the amount of diffusiion will be somewhat controlled by the amount of exchange through the 5" hole.

Beez · Posted: September 3rd, 2010, 10:49 am

Rangeball wrote:

Is the rate of diffusion tied to the size of the hole or the area of contact between the water and the bleach?

I'm thinking of a 5 gal bucket filled with bleach then submerged. Say a 5" hole is cut in the lid. The area of contact between the bleach and water is 5". However, over time the upper area of the bucket becomes filled with water (as bleach is diffused), and the contact area between water and bleach is now the full diameter of the bucket. Is this greater contact area going to cause higher FC levels or will the 5" lid opening provide steady FC levels?

I can't answer your question with any level of certainty as I only have assumptions on the matter, but I almost tried a similar experiment to the one you propose. :mrgreen:

I had ideas of a large vessel with an adjustable opening that might allow me to regulate the rate of diffusion, but as I worked throught the logistics in my mind I suddenly thought: "This is ridiculous! This work has already been done, it's called the Liquidator!"

Rangeball · **Joined:** May 25th, 2007, 4:00 pm **Posts:** 717

yes, and it has a large surface area for contact interaction, but also a valve to control outflow and subsequent FC.

Plus, a 5gal bucket with lid is a tad bit cheaper

Beez · Posted: September 3rd, 2010, 12:56 pm

Rangeball wrote:

Plus, a 5gal bucket with lid is a tad bit cheaper

True, but it will take a lot of experimentation and fiddling to get it to produce the right level for your target FC. :wink:

Also, I ran into one other little nasty side effect during my experiment. A leaf or two got up under the jugs and left a brown tannin stain before I removed them. Not a deal killer, but a PITA.

Rangeball · **Joined:** May 25th, 2007, 4:00 pm **Posts:** 717

One possible place to start would be in the first post of this thread. The OP said his pool uses 3 96oz jugs every 10 days, and it took 10 days to empty a jug via diffusion. He was using 3 jugs, so possible one could put the same diameter size hole as a 96oz jug, one hole for every bottle needed per 10 days?

For example, my pool would use 10 96oz jugs in 10 days. If I drilled 10 holes in my lid the same diameter as the 960z jugs, maybe?

Of course, I'd need a 7.5gal bucket and lid

Beez · Posted: September 3rd, 2010, 1:24 pm

Rangeball wrote:

One possible place to start would be in the first post of this thread. The OP said his pool uses 3 96oz jugs every 10 days, and it took 10 days to empty a jug via diffusion. He was using 3 jugs, so possible one could put the same diameter size hole as a 96oz jug, one hole for every bottle needed per 10 days?

For example, my pool would use 10 96oz jugs in 10 days. If I drilled 10 holes in my lid the same diameter as the 960z jugs, maybe?

Of course, I'd need a 7.5gal bucket and lid

Yeah, it was that initial post that got me interested in the idea, but my results don't jive with his...in 7 days, not quite half of the bleach left the jug.

Try it yourself and see if you can repeat his results. You really don't risk much, just sink one jug and see how long it takes to empty.

Rangeball · **Joined:** May 25th, 2007, 4:00 pm **Posts:** 717

I can do that, but think I will put the bleach in a milk jug so I can easily monitor the level.

ssa · Posted: October 7th, 2010, 6:43 pm

Interesting. I bet placing the jug near the water return can accelerate the bleach leaving rate.
I can see myself making a pvc pipe case to hold it. The plus benefice is that, the acceleration only
happen when the pump is running. And I don't have to worry about the vacuum robot bumping
into the jug.

attr · **Joined:** March 3rd, 2012, 8:47 pm **Posts:** 13

Just an idea to find out a little more about what is happening

wedge a sponge into the top and see if you get similar results . if so it would seem diffusion is what is taking place.

also wondering if a "chicken feed" system would make the use more constant.
think of one of the "automated fill dog bowls" taht use a inverted bottle to refill a smaller pan.
sink this in the pool and have it with a deeper pan (5 inch?) but have the opening to the inverted bottle be really close to the bottom ( 1/2 inch lets say)
if water and CL act the same as water and air ( all of these are FLUIDS) then this idea may work and add the same amount of CL each day)

ehh i see me filling up a bathtub and playing around with this on a small scale....
dang you rich for pointing me to this thread ><

carlscan26 · Posted: March 18th, 2012, 11:43 pm

It is absolutely diffusion that is taking place. Also, air is not a liquid. The method you're suggesting wont need the pan as it will always be filled by the pool as it is submerged. You could just hang the bottle but then Aren't you doing the same as floating or sinking a bottle of bleach?

I like the idea of a floater for FC. But honestly my LQ provides the same functionality as the OP was looking for as I only refill my LQ every two weeks.

I also really don't see this being safe for a vinyl pool unless you keep it floating in the middle of the pool so it never hangs out at the wall or corner.

march2012 · **Joined:** January 21st, 2012, 10:09 am **Posts:** 144

Beez wrote:

Well, one week into the experiment and I'm ready to give up...at least for now. :mrgreen:

The bleach migrates out of the jug v e r y slowly. Just to give you an idea how slowly: I sunk one jug last Thursday. Then on Monday I sunk another because I could still clearly see bleach in the first one. Today I grew impatient because it is rainy and I wanted to make sure I had enough FC, so I pulled up the jugs and emptied them into the pool. Combined they raised the FC by 6. One full jug of bleach raises the FC in my pool by 4! So only 2ppm had gone from the jugs and one of them had been submerged for a week.

I realize that this process could be accelerated by increasing the surface area of the interface between bleach and pool water by poking additional holes in the jugs, but the enticing part of the original idea was to use the jugs as they are with no modification.

It is a fun idea to think about, but IMO it is impractical for real usage. Theoretically, the right container with an adjustable opening might work, but if you were going to that much trouble it would be much better to just buy a Liquidator.

if you could figure out the appropriate size holes you could make a plastic device that just pokes onto the side of a bleach bottle and creates the correct size hole. I was thinking about buy a makerbot which can make plastic objects in any shape. This would let you test many different sizes of holes and form factors. Alternately you could make a custom thing that has the following properties

1) sinks when there is bleach
2) has the right size holes for the correct diffusion rates
3) floats when there is no bleach
4) allows you to pour bleach into it
5) be able to add a battery powered stirrer to speed up the mixing of bleach and water
6) sinks correct side down

JasonLion · Posted: April 7th, 2012, 2:12 pm

That reminds me of this thing. Of course it works with tablets instead of bleach,but it does have the cool sink/float thing going on.

carlscan26 · Posted: April 9th, 2012, 1:13 am

I've seen those!!

slow and steady chlorination idea- first tests

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