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