Pool Chlorinator

[marc]

I'm a newbie and want to build an electronic pool chlorinator using an alternating DC supply onto two copper electrodes. Can someone please help me with my first project!
Thanks in advance...

 

[kinjalgp]

alternating DC supply

Do you mean pulsating DC? or anything else?

 

[marc]

dc output

Nope, I need the polarity to be logically switched (12V 0.5A) across the electrodes so they won't 'plate' and wear unevenly. I thought of a 555 timer switching a relay but I'm sure there is something better. The timer should time say a minute (+) on the electrode and then switch to (-) for a minute and so on...

 

[mechie]

Generation of Chlorine

Are you really aware of what you are attempting here ...
For a swimming pool can you monitor the total chlorine level in the water in order to maintain safe levels (too much is dangerous, not enough is a waste of time).

See **broken link removed** for a safety data sheet.

See **broken link removed** for a commercial product.

You will need to produce a saline solution, electrolyse it, allow hydrogen to escape safely, descale the electrodes regularly AND measure the pool's chlorine level.

I don't doubt that it can be done but it is a challenge :wink:

 

[herbymcduff]

Re: dc output

Nope, I need the polarity to be logically switched (12V 0.5A) across the electrodes so they won't 'plate' and wear unevenly. I thought of a 555 timer switching a relay but I'm sure there is something better. The timer should time say a minute (+) on the electrode and then switch to (-) for a minute and so on...

Actually, I think it to be quite simple to use a 555 timer. You can just run it in astable multivibrator.

 

[marc]

I did a little more investigating and believe I should not call this a Chlorinator but an Ionizer. Check this site:
**broken link removed**

How will I connect the 2 electrodes if I use a 555 timer running astable if I want the polarity to swap over them for a period of time :? I'll be stoked if I can build one of these babies! I've already got a unit to work in a buddies pool, but it does not change polarity. (Straight DC power supply onto copper electrodes)

 

[mechie]

Chemistry in a bathchair

This 'Clearwater' thing claims great things - ignoring the fact that copper and silver are not particularly good for you in quantity.

As one electrode of their system is silver to produce silver sulphate (where did the sulphur come from?) how do you emulate this with two copper electrodes?.

In short I think a flashing LED in a jar of jellied eels will probably achieve as good a sterilisation of your pool - their quotes about obsolite statistics are misleading at best.

I intend to ask some working chemists if the theory of this device is sound as I am genuinely curious about this, NASA or real world!

 

[marc]

I only used copper electrodes due to availablility and cost. So I'm killing algea but not bacteria... :lol: Looking forward to your feedback.

 

[mechie]

A chemist's considered response ...

It does work (allegedly) on small supplies but it has to get past the natural protective coating on the bacteria and algae. Chlorine works by breaking down the cell walls causing a collapse of the cell. Copper works by poisoning the cell !!! The silver combines with the sulphates already present in the cell provided it can get in there! You need additional treatment as well. It would be ok for a spa pool or a domestic pre-treated supply but you still need chlorine, just less of it. The copper is already there in drinking water anyway (pipes). Besides, we need some exposure to bugs to get our immune systems working.


If both electrodes are copper they will both produce copper ions so the polarity is irrelevant -- any switching frequency will even out the copper depletion (corrosion).
A simple two-pole, changeover (DPCO) relay could swap the electrode duty (anode - cathode) from a simple DC supply.
The relay could be switched by a simple 555 timer circuit.
-OR-
If one electrode is connected to a 1 volt (for example) positive supply ...
the other electrode could be switched between 0v and a 2 volt supply, the result is the same.
-OR-
Just use a transformer to step down and isolate from mains ...
AC to the electrodes it's just a faster switching frequency !

For a silver electrode - go to a second-hand shop and buy old cutlery :wink:

 

[marc]

thanks a ton for the input!!

 

[bradnz]

I'm an electronics engineer and am planning on building 1 of these "ionisers" or whatever you want to call it.

The simplest circuit to build for a novice would probably be a 555 based with a DPDT (double pole, double throw) relay to switch the DC polarity.

I am also considering using AC, all i would need then is a step down transformer from mains to say 12V.
I'm not sure if this will allow enough time between polarity changes so if anyone can answer this for me I would appreciate it.