Absolutely, You need Stabilizer. Here is a bit of a testimonial. Being a real card carrying "Big Tall Dumb Guy" with a SWCG, my scatter brain told me I didn't really care too much about the CYA (stabilizer) levels. So when I replaced my pool liner last year and installed a SWCG, I added some CYA but not enough. My Chlorine levels were good with my CYA at 25 - 30 PPM, AND ALL SEEMED GOOD.

After all, my chlorine is FREE, Right? Wrong! Chlorine isn't "free" when you have to run your pump twice as long to keep the Chlorine levels up (NOT TO MENTION BURNING OUT YOUR CELL).

I had to run my system for 7 hours a day to keep from running out of chlorine at sunset. I decided to stop being so stupid and I raised my CYA to 45 ppm and I am now running my pump for 4 hours a day. The $10.00 bottle of stabilizer will save me hundreds (Plural) yes hundreds of dollars in electricity.

You can learn a lot from a BIGTALLDUMBGUY!