Sprinkler Water Runoff into Water Gardens

I am fairly new to water gardening but have discovered an unattentional side effect of sprinkler runoff into my water garden. Let me begin by saying that my wife and I built our small (60 Gal) water garden in our backyard last summer. We populated it with 12 'feeder' gold fish from the local pet store in hopes of the fish eating mosquito larva from becoming adult blood suckers. Well luckily enough our small water garden flourished over the hot and dry summer months we get here on the Front Range of Colorado. The surviving 8, now full size gold fish made it through the summer and early fall months before I brought them inside for the winter. Last year we enjoyed a relatively maintenance free water garden surrounded by both perennial and annual flowers, the sound of running water we could hear through our bedroom window. The only issue we had was the evaporation of the pond water due to the hot, dry climate. My solution to this problem was to run a line from the drip system we had installed to keep the newly planted trees, plants, and shrubs surrounding our water garden, directly into the pond. It worked, the sprinkler system than ran for 15 minutes a day, 3 times a week, was enough water to keep my pond full of water. Once the winter cold subsided, in early March, I filled the pond back up, let the 6 weeks of time recommended for growing the beneficial bacteria to grow, I re-introduced the healthy gold fish I had grown last summer back into their summer home. Unfortunately I had a problem 2 weeks later... An algae bloom I have never seen before. I couldn't figure out why I had no problems with algae last year, but yet this early in the season I had a pea soup of a pond. Thinking I didn't have the pond cleaned enough, I proceeded to clean the mechanical filters almost every other day with no avail. I looked into a UV filter which run upwards of $200 to solve my problem but was puzzled by the fact I didn't have this problem last year, why now? Well I found out last week... The nights are getting warmer and after all its past Mother's day in Colorado which traditionally means we have the green light to turn our sprinkler systems back on. Not more than a week later the water in my pond has cleared up. Why you ask??? I am not a biologist or chemist, but the only answer I can come up with is that the run off from the drip system in my water garden is getting into the pond. Why is this making the water clearer??? Well in most Metro areas, chlorine is added to the drinking water to prevent bacteria, including algae from growing in the drinking water. That's right, the very chemical that is keeping our drinking water safe is clearing the algae from my pond. PLEASE don't think that this is professional advice, most if not all water garden sites say that water must be de-chlorinated before being put into water gardens in order to keep your fish alive, this is just one man telling a story about his theory on why his water garden and 8 hearty gold fish have clear, not green, water to swim in.