Howdy Shereen,
It's not that the Powersun is inherently bad due to something like having an incorrect spectrum, but rather that it requires an added level of diligence by the keeper to insure that the UVB levels combined with temp levels are balanced correctly if even possible. The advantage of having a separate UVB source and heat source is that you can independently tune their positions for optimum performance.
The fact that your chameleon closes its eyes during the day is a strong reason for concern. It is unlikely that it is related to your Zoomed Reptisun 5.0 linear tube so long as it is kept ~6" to 12" away from him at his basking spot. When eye closure begins, there isn’t a heck of a lot of time to sort things out

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