Switching from Synergy to Dichlor and Trichlor

[Thinkly]

I used Synergy tabs and Clear in my first year pool this season. I was thinking about switching to just Trichlor and Dichlor and maybe some Borax to simulate the same thing without the same expense.

Does this sound reasonable? What will i miss?

 

[spishex]

That's the right way to go. The only thing you'll miss is the added expense of buying the old product.

 

[chem geek]

Synergy, as shown in this MSDS file, is just Trichlor with some Borax to not be quite so acidic. Synergy Clear, as shown in this MSDS file, is just Dichlor (a pretty weak form of it -- more impure than even the dihydrate form).

However, have you read the Pool School and are you aware of how quickly the Cyanuric Acid (CYA), aka stabilizer or conditioner, will build up from use of these products?

For every 10 ppm Free Chlorine (FC) added by Trichlor, it will increase CYA by 6 ppm.
For every 10 ppm FC added by Dichlor, it will increase CYA by 9 ppm.

Even if you had a low 1 ppm FC per day chlorine usage, continued use of Trichlor would increase CYA by over 100 ppm in 6 months. If you used Dichlor, then the CYA would increase by over 160 ppm in 6 months. This assumes no water dilution, so no splash-out, backwashing, rain overflow, etc. (but not evaporation and refill since that only removes water and not CYA). If you do not raise the FC level as the CYA climbs or do not use an algicide (at extra cost), your pool is much more likely to get algae growth. You can instead maintain your pool using unstabilized chlorine (chlorinating liquid or bleach) and keep the CYA level constant, only occasionally using Trichlor to bring up the CYA if needed. The downside with chlorinating liquid or bleach is that you'll have to add it every day or two unless you have a pool cover opaque to UV in which case you could add it twice a week.

Richard

 

[polyvue]

I used Synergy tabs and Clear in my first year pool this season. I was thinking about switching to just Trichlor and Dichlor and maybe some Borax to simulate the same thing without the same expense.

You'd save even more by using liquid chlorine...

Whatever you elect to do next year, do have a good test kit handy because you'll need to closely monitor CYA and TDS, not to mention borates, FC, CC, etc. Using trichlor regularly will likely contribute to a steady increase in cyanuric acid -- but perhaps this is old news to you?

If you have a lot of spash-out (or a filter that requires regular backwashing) you may not have the problem with CYA accretion that other pool operators have.

• EDIT See chem geek's comments, above, for details on this. END EDIT
  Edited by Greg - October 19, 2009 7:30pm