That's the problem with inexpensive timers is that they don't water enough times during a 24 hour period to be adequate for hydro systems that use
grow rocks. I have to water every half hour to keep my plants from wilting and to get the benefits from force feeding my plants for them to grow faster.
I use a Dayton 1 hour cycle timer that repeats every hour with one minute pins that I add depending on the size of my gardens. It cost about 70 dollars but I can use it for all my gardens by putting a flow control valve on the smaller gardens to water to the correct height as the largest garden.
Ron