I was planning on using it after getting the algae under control.
How does THAT work? You're going to find out what you're working on . . . after you finish working on it??

Get a kit, now! Test the water, now! Tell us what's there, now! (Right now, you are flying blind, at low altitude, around mountains!)

The good news is, none of the algaecides you've used are a problem. In fact, they are all the SAME thing. The Kem-Tek Polyquat (60%) is just the concentrated version of the other two products which are both a 50% dilution (30%). The bad news is, they aren't really going to help you in your current situation. So save what you have to use AFTER your pool is cleaned up, when you go on vacation.

Using the 68% cal hypo CAN help, if you used it correctly. But you need to know more, and I need to see test results, before you try to use that. Depending on your current pool water conditions, it could make things worse.

Since I really don't know what your current water chemistry is, the only SAFE form of chlorine to use is bleach. Assuming your water depth averages 4 feet, you have about 18k gallons, and a PF of about 7. So . . . each gallon of plain 8% household bleach will add a little more than 4 ppm of chlorine.

1. Buy a cheap OTO / phenol red drops kit (unless that's what you have.)
2. Buy (24) gallons of PLAIN store brand 8% bleach.
3. Add (6) gallons tonight. Test the chlorine in the AM -- if the chlorine level is not ORANGE or orange-tinted yellow, add a gallon of bleach VIA THE SKIMMER after making sure there are NO other chemicals present in the skimmer.
4. Complete the info forms:
http://pool9.net/pf-pool-form/
http://pool9.net/pf-hist-form/
5. If you haven't already, order a K2006: http://pool9.net/tk/
6. If you expect to take more multi-day vacations or business trips this swim season, order the Taylor phosphate testkit, too. (same link)
7. Test your pH the evening AFTER the first (6) gallon dose, then test chlorine. Report results. If the algae has not died OR if the chlorine level is not DARK yellow to ORANGE, add (6) more gallons VIA THE SKIMMER.
8. Post results.