If "CYN" is stabilizer then your problem is obvious: You need to shock your pool up to a FC level of about 20ppm and hold it there till everything in your pool is dead. What you describe sounds more like a hot tub than a pool: 1500 gallons, 6'x8'. I would start by adding a quart of bleach--8.25%--to your pool, and having the water tested.

Meanwhile you need to get a better test kit. If there's a WalMart nearby, look for the HTH 6-Way drop test kit, and pick up a gallon of steam distilled water. You can dilute the pool water with the distilled water to double, triple or quadruple the test kit's chlorine reading. 3 parts of distilled to 1 of pool water will mean that "5" on the tester really means "20"...which is where you need to be.

As for the borax and baking soda--not appropriate. Baking soda with a TA of 145 is about the worst thing you can add. Borax raises pH, but borates in it inhibit algae. Muriatic acid will lower pH but at 7.8 it's tricky to lower it in such a very small pool. So that was pretty bad advice.