RP rightly suggests a diagnosis and a fix for the problem. However, your post raises a general problem. In plumbing, the only valves that are designed to be turned off and on on a frequent basis are fixture faucet valves and toilet flush valves. Other valves (fixture shut-off, water heater supply, and main water supply valves)are meant to be closed infrequently if ever in the normal course of business). These latter applications are best served by full-bore valves (gate and ball valves) to optimize water flow. Throttling vales (mainly “globe” valves with washers)restrict flow too much to be worth installing in such places…indeed most codes prohibit them in those applications.
The problem with gate valves is that they tend to bind and/or leak when they are cycled too frequently.
If you absolutely must open and close the valve on a daily basis, you should replace it with a good quality full bore ball valve. This type valve will give you the best service for your application.