If you CoBs are drawing 2 Amp or less you could add a TCO thermal fuse for $0.60 using a Panasonic EYP-2BN143. You could also add redundancy and use two pumps. What you would do is add a water tank higher than the fixture and allow gravity to make the water to flow from the tank through your heatsink to the fish tank. Then you use two pumps to pump the water from the fish tank to the gravity tank. I built a "Water Tower" out of 4" PVC. While building I found a better was to do it with just the center pillar at a much lower cost. The upper "Water Tank" was not necessary. Gravity does a very good job of keeping the tank empty. This one was about $100 and holds about 3-4 gallons.