Justin,
If this is a recent setup, the cyano bacteria is just part of the cycle. If your water parameters are good, chances are it will die off. Dechlorinating the tap water is generally a good thing, however it will do nothing to remove phosphate and silicates. These 2 will be the main food source for your intial algae blooms when first starting up a new tank. The best way to control this is to limit the amount of feeding (if you have fish?) and most definately use ro/di (reverse osmosis/deionized) water. If you do not have this system, look for ro/di water in your supermarket. Distilled water will be good too, but more costly. I fear that since you're doing large weekly water changes and not removing phosphates/silicates, you're only compounding the problem and this cyano issue will plague your tank.
