FC + CC = TC, so either there is a testing error or something was listed incorrectly when you typed your post. Might want to run those tests again. If you do indeed have a CC reading, then you do need to shock your pool.

Is this a new pool? If not, have you used any cal-hypo in previous years? If so, it would probably be a good idea to run the calcium hardness test. (You are right that vinyl pools do not need calcium but use of cal-hypo over time can run the CH reading up and that can contribute to cloudy water problems.)

Your pH at 6.8 is CRITICAL. Test kits won't show lower than 6.8 so a 6.8 reading might actually be much lower. Need to get it above 7.0 ASAP. After you add Borax, don't have to wait days to add more. Wait 2-3 hours to let it circulate, retest and redose as needed. In a pool this big and pH that low, I think you can add an entire box until the pH starts to move and then add smaller additions. By the way, trichlor is very acidic and will lower pH. So, if you use trichlor often, that may be the reason your pH wants to stay low. ASAP or low pH can damage your pool.

Regarding algaecide, some people use it only at closing; others use it routinely as part of their maintenance. It is OK to use, but make sure you only use 60% polyquat. It is a much better as a preventative than it is helping after you have an algae bloom going.

Take a look at the chart at the following link to help you figure out needed chlorine levels for shocking and for maintenance.

http://www.poolforum.com/pf2/showthread.php?t=365

Repost with retested chlorine numbers and calcium hardness reading. Hope this helps.