Naked Science Forum

Non Life Sciences => Chemistry => Topic started by: ar on 15/02/2006 16:12:18

Title: Soap bubbles in the fountain
Post by: ar on 15/02/2006 16:12:18
I have a water fountain that tends to suffer from jokers dumping soap powder, washing up liquid, shampoo into to make it foam.
Would running it with a brine solution instead of tap/rain water be able to beat the occasional high concentration of detergents?
Anybody got any other ideas on how to stop it foaming?  (It's in a public place so has to comply with UK regs [:(] so nothing to caustic!).
How do the people who run the big public fountains manage to beat the would-be foam party 'little-darlings'?
Title: Re: Soap bubbles in the fountain
Post by: ROBERT on 15/02/2006 18:26:58
Possibly use swimming pool products :-
Several factors can contribute to foaming in pools:

 Tile cleaning phosphates.

 Practical jokers with a box of soap.
Anti-foaming agents are available.
Chitin products like Sea-Klear can prevent or eliminate foaming from occurring.
 The Natural Chemistry line of enzyme products are also very effective anti-foam agents"".

Title: Re: Soap bubbles in the fountain
Post by: ar on 16/02/2006 11:27:43
Thanks Robert; I've emailed them to ask about their products.

Anybody got any suggestions for running alternatives to plain water?  I suppose we could model the falling water in glass and play a tape recording of the noise - it would fool some of the people!  But is there a liquid that is relatively non-toxic, doesn't foam and has a viscosity close to water? (I suppose I could argue it as a political statement if we ran it on oil rather than water [:)] )

The 'fountain' is really more of a series of waterfalls set into a wall and the artistic effect is created by the noise and turbulence as the falling sheet of water hits the collecting pond.  My involvement is as an engineer, working with the artist, to try and solve the foam-party joksters.  

What is the chemistry involved when a soap solution is added to the water?  Is there any way of breaking the process?  Is it as simple as changing the Ph of the water or what would the effect be of say, positioning some dc powered electrodes just where the water 'lands' (in effect a mini hydrogen-generator) to change the foaming reaction?   I presume the basic problem to solve is lowering the surface tension that the soap solution is encouraging?

There must be an 'elegant' (and fun) way of solving this problem.
Title: Re: Soap bubbles in the fountain
Post by: ROBERT on 16/02/2006 13:38:55
Here is another possible source of anti-foam agents:-
Some are used in food manufacture so are presumably safe for the "general public",
 who may be tempted to drink from your fountain.

Creating an acid (low pH) or alkali (high pH) solution could be hazardous to the public:
 it could cause chemical burns to skin & eyes.

Your idea of putting "electrodes" into the water is potentially fatal.
Title: Re: Soap bubbles in the fountain
Post by: ROBERT on 16/02/2006 14:11:54
Another possible source of anti-foaming agents for your fountain : fish pond products:-

(I would try the swimming pool products first: they allegedly work on practical joke quantities of detergent, and are designed to treat a very large quantity of water, so should be the most cost effective.)