Silk balance vs Hot Tub Serum

As the spa products industry is finally starting to recognize the benefits of “quaternary ammonium cations” (sometimes called “QUATs”), the concept of a regular water maintenance product is starting to become  more prominent.  This post is about two such products — both of which hold familiar places in the market.

Those of you who follow my work know that I regularly use the product called, “Hot Tub Serum”, or “Serum Total Maintenance”.  When it was first introduced, I was reluctant to use it but over the years I have become familiar with its extraordinary benefits — most notably as a way of  extending the number of days that the spa can be  “left alone” (when I’m on vacation, for example).  There is a secondary benefit, in the form of a pH buffer, as well.

With this background, a similarly positioned product from Silk Balance comes to mind as an alternative to Hot Tub Serum, so I thought it would be fascinating to test the two products against each other within the following context:

1.  Well-maintained water:  Almost any product can be impressive when there are unsolved problems with the water.  I have no interest in a rescue product, but I do have interest in knowing how a given product will benefit those of us who take good care of our water.
2. The sanitizer decay rate:  This is of great interest to me because it tells me how long I can go on vacation or leave the spa un-attended — without using a floater, for example.
3. To a lesser degree I’m interested in secondary marketing claims, such as  “softens the water” (whatever that means), or even “greater water clarity”.  I have a well-established maintenance regimen and my water is clear enough, but if I could see a real improvement in clarity I would take notice. Clear is good!  Conversely, claims of “soft” water are more about selling emotion than science and depend largely on perception (and thus emotion, and even placebo effect!).  It’s difficult to objectively test this, although I did try…

1. Interestingly enough, I actually did find an objective measure of “it softens the water” —  I found a small decrease in Calcium Hardness over the life of the product (until it was consumed)!  Given my experience with an early formulation of Silk Balance “Clean Start” (which was nothing more than ordinary Borax in an expensive container), the possibility occurred to me that the Silk Balance product I was now testing might also contain some Borax (Without getting too technical, Borax tends to “soften”  by reducing the measurable Calcium Hardness present in the water).    The difference I measured was too small to be important, however (on the order of 20ppm reduction), especially considering the possibility of measurement error.  Getting someone to believe that a product “softens” water could be accomplished with the surfactant properties of Borax as well — for example making the water feel slipperier.  This would give one an excuse to believe in the magic promised on the bottle.
2. I found that the pH buffering capabilities of the product are real, but not that noticeable and not as effective as the pH buffer in Hot Tub Serum.  Even though (per label directions) I added the product when my water parameters were within acceptable ranges, I found that it didn’t really mitigate the problem of pH drift. I just kept adding acid I normally do, to keep pH from rising.  This causes Total Alkalinity (TA) to drop as a consequence, as many others have discovered — which by the way does not cause the sky to fall.  Separately, I have found that the use of a pH buffer, in general, doesn’t change the overall or average amount of acid you have to use to reduce pH — it just makes the pH changes more gradual.  In my spa, TA can go as low as 40ppm as I keep adding acid to combat upward pH drift.  Since TA itself moderates changes in pH, a value this low for TA is quite risky because a sharp  drop in pH is likely and could spell trouble.  Accordingly, any pH buffering contribution from a maintenance product is a good thing, and the Silk Balance product did contribute something.  Given the “soft water” claims of the product, I’m fairly certain that it contains Borax — which is a pH buffer in its own right, in the form of Borates.
3. The effect of Silk Balance upon the sanitizer decay rate was, sadly,  a non-existent.  In fact, the headline is that the use of Silk Balance is no different from using nothing at all!   To illustrate this I prepared the graph below using real data (apologies for the way this site “optimizes” images):  The blue line represents my decay rate when Serum Total Maintenance is in the water.  The other two lines represent Silk Balance and “doing nothing”, respectively (this is the sanitizer decay rate when neither Silk Balance nor Hot Tub Serum is in the water).